computational and experimental analysis of ballast water exchange

Naval ENgiNEErs JourNal 2006 #3 ��

Computational and Experimental Analysis of Ballast Water Exchange

Wesley Wilson, Peter chang, Stephan verosto, Paisan Atsavapranee, David f. reid and capt. Philip t. Jenkins

IntroductionBallast water exchange (BWE) has been and remains the primary management practice with widespread application for reducing the spread of nonindigenous aquatic species via ballast water (ABS, 1999; Drake et al, 2002; Rigby, 2001a). BWE was intended as an interim measure while more acceptable and possibly more effective or reliable methods are developed. While BWE by itself may not be a viable long-term solution, its use will likely continue for the foreseeable future. The recent International Mar-itime Organization Convention on Ballast Water Management (IMO, 2004) sets a very aggressive agenda in order to eliminate all BWE by 2016, but this schedule may be difficult to achieve. Thus it would be useful to fully understand the ballast water exchange process, the flow dynam-ics inside a ballast tank during exchange, and how tank architectures affect the outcome.

The goal of BWE is to replace coastal ballast water (and entrained organisms) with mid-ocean surface seawater. There are two types of BWE approaches: reballasting (or empty-refill), and flow-through (or flushing). The former requires that ballast tanks be emptied completely and then refilled at sea, while the latter requires pumping of mid-ocean water, usually entering at the tank bottom, into a full or partially full ballast tank and allowing the water to overflow the tank for a given (usually three) tank volume multiple (Rigby and Hallegraeff, 1994; Hay and Tanis, 1998; Rigby, 2001a). It should be noted that the flow-through target of three tank volume overflows is based on a theoretical calcu-lation that assumes perfect and instantaneous mixing between the original ballast water and the incoming mid-ocean water (Hay and Tanis, 1998). In practice this is not likely achieved.

AbstractThe objective of the present study is to use experimental and computational fluid dynamics (CFD) methods to examine the flow behavior inside ballast tanks during flow-through ballast water exchange (BWE), and to in-vestigate the exchange effectiveness. Validation efforts are conducted based on comparisons with data collected in a 1/3-scale model of a portion of a typical ballast tank for a bulk carrier. Comparisons between the measured data and computational predictions are in good agreement. Numerical simulations are also performed for a typ-ical full-scale ballast tank in a 35,000 dwt handysize bulk carrier, a ship type that represents a large proportion of the oceangoing vessels that ply the Great Lakes trade routes. The results of this study may help explain the variable results of ballast water exchange experiments documented to date, lead to ballast tank structural modi-fication recommendations to improve overall ballast water exchange effectiveness, minimize deadspots, reduce sediment deposition and accumulation, and provide the insight and knowledge to select and enhance treatment technologies, thus reducing the threat of coastal invasive species being discharged in coastal ecosystems.

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Summaries (Rigby, 2001b; USCG, 2002) of experimental shipboard attempts to quantify the effectiveness of BWE based on a variety of ex-perimental approaches found that BWE appeared to achieve water replacement as high as 88-99% of the original water carried in the ballast tank. However, guidelines and regulations require consistent achievement of 95% or better. On-board studies have often involved different ships, different experimental conditions, and different sampling and analytical approaches. Experiments have also been conducted on cargo holds designed for alternate use as ballast tanks, or in forepeak tanks. There are many factors that can contrib-

ute to variances in experimental results such as sampling techniques, tank geometries, exchange approaches (reballasting vs. flow-through), flow rate during flow-through exchange, and starting salinity of the original ballast water compared to the salinity of mid-ocean water, to name a few. Obtaining samples from a ballast tank during exchange is not a trivial procedure. In addition, such on-board experiments generally rely on measurements taken at the overflow outlet of the tank, and do not necessarily represent the volume mixture that remains in the ballast tank. Limitations on tank access and sampling equip-ment generally prevent collection of more than a few spatially and temporally distributed samples, and better sample/data resolution is needed to assure the results are representative of conditions throughout the tank.

There are many different types of ballast tanks (Figure 1) and most are structurally complex, composed of interconnected bays separated by girders, floors, frames and plating, with associ-ated lightening holes, limber holes and slots for drainage, and longitudinal frames or stiffeners (Fig ure �).

The goal of the present work is to develop an experimentally validated computational tool that can be used to investigate the flow phenomena present in these types of tanks and to assess the exchange efficiency during flow-through BWE. These computational methods may also provide insight into potential areas in the tank where sedimentation may occur, as well as possible structural modifications that might improve the tank designs.

1/3-Scale Experimental ModelA 1/3-scale experimental model of four contigu-ous bays of a typical ballast tank, two double bottom and two side bays, was constructed of 1-inch-thick acrylic plate except for the top, which was made of 1/8 inch steel plate (Figure �). An extensive effort was dedicated to ensuring that the appropriate non-dimensional param-eters were scaled correctly throughout the ex-perimental model’s design. Richardson numbers

Figure 1: Typical Bulk Carrier Mid-Section

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Figure �: Photograph of Structural Details (Upper Wing Tank)



were calculated at various points in the experi-mental model and were found to scale satisfac-torily. The Richardson number is the ratio of buoyancy to inertial forces, and is considered to be the most important parameter for two-fluid mixing. Note that the term “1/3-scale” refers to true geometrical scaling in that the height of the tank is 1/3 of a full-scale tank and the horizontal dimensions correspond to four bays of a full-scale tank with 1/3-scale dimensions.

The model facility was designed to support varying flow rates and consists of one 500-gal (1,893 l) premix tank, two 500-gal supply or waste tanks, one 200 gpm (757 lpm) centrifu-gal pump, one vortex shedding flowmeter, two class 4 lasers, one class 3B laser and the 1/3 scale acrylic model. An inlet pipe extending from the tank top and bellmouth were also constructed from acrylic and were placed with the lower edge of the bellmouth at a height of 1 inch from the tank bottom. The facility is located in an environmentally conditioned space equipped with approved class 4 laser safety devices. Sizing of the waste and supply tanks was based on the model capacity of approximately 460 gal (1,741 l) and a single flow-through exchange.

Experimental ApproachLaser Induced Fluorescence (LIF) was used to obtain two-dimensional temporal measure-ments of the concentration of the fluid fraction of the two fluids at three planes inside the tank, strategically chosen in areas where significant mixing occurs, as well as in the exit pipe. Tests were performed with an inlet flow rate of 65 gpm (246 lpm) which corresponds to a 1000 gpm (3,785 lpm) full-scale flow rate. The flow rates were obtained by Richardson scaling of the flows in the vicinity of the inlet bellmouth.

Richardson scaling requires that the ratio of the ship and model scale flow rates are the 5/2 power of the scale ratio; therefore, a 65 gpm model scale flow rate gives the same Richardson scaling as a 1000 gpm full-scale flow rate. The experiments were run for only one model-scale tank volume exchange due to cost and limited

reservoir capacity. One tank volume exchange tanks 350 seconds with an inlet flow rate of 65 gpm in the 1/3-scale experimental model.

During the physical model experiments, the original fluid in the experimental tank (in this case, fresh water) is “tagged” with rhodamine-6G dye. The incoming (exchanging) fluid, repre-senting mid-ocean saline water, is clear. Selected two-dimensional planes inside the tank are illuminated by a laser light sheet from a pulsed Nd:YAG laser with an output of 200 mJ/pulse at 532 nm and recorded using Hitachi KP-F120CL digital cameras with an image resolution of 1392 x 1040 pixels. The rhodamine dye molecules, when excited with the laser sheet, fluoresce with an intensity corresponding to the concentration (volume fraction) of the tagged fluid. By careful calibration using normalization by a “reference” image, this technique not only yields useful visualization of the mixing phenomena within the tank, but will yield an accurate quantitative measurement of the fluid fraction of the tagged fluid. For a detailed description of the technique, see Atsavapranee and Gharib (1997).

Four areas were selected for visualization, data recording and comparison to the CFD model. These included: flow at the inlet bellmouth; flow over a stringer; flow through a lightening hole, and at the discharge outlet of the model. The

Figure �: 1/3-Scale Experimental Model.


experiments commenced by setting the supply flow rate while recirculating the saltwater back to the supply tanks rather then into the experi-mental model ballast tank. When the rates were steady and trapped air eliminated, the lasers and cameras were energized. The saltwater flow was then shifted through the model. Trends in the mixing and dilution of the original fluid during exchange are obtained from the experimental data. This information is used to evaluate the accuracy of the computational predictions.

Figure � shows sample LIF results from the experi-ments. The flow direction is from right to left. Figures 4a and 4b show flow of saltwater through

a lightening hole (upper right of each figure) and limber hole (lower right of each figure) at 10 s and 60 s respectively. The images are captured at a rate of 30 frames per second by three CCD cameras focused on three critical locations in the tank, for a total of 90 images per second. Each image is approximately 1000 pixels across the top and 1300 pixels across the side.

Computational MethodThe CFD simulations are performed using the commercial viscous flow solver, Fluent, devel-oped by Fluent, Inc. The code uses a cell-cen-tered finite volume approach to solving the governing equations of mass and momentum. In addition, a transport equation is solved for the volume fraction of one of the fluids, with the algebraic constraint that the volume fraction of both fluids must sum to unity. The convection terms are discretized using a second order up-wind method, while the diffusion terms are dis-cretized using the second order accurate central differencing scheme. The turbulence closure used the RNG k-ε model. In order to solve for the physical and temporal distribution of the two fluids, the mixture multi-phase model in Fluent is used. This seems appropriate for this type of problem, where the two fluids are miscible, and have densities that are nearly equal. The time derivative terms are discretized using the first order backward implicit scheme. Currently this is the only method available for temporal dis-cretization of the volume fraction equation. The PISO pressure-velocity coupling method is used, and the discretized equations are solved using pointwise Gauss-Seidel iterations, and an alge-braic multi-grid method accelerates the solution convergence. A series of calibration runs were performed in order to arrive at the optimal set of run parameters. These were determined based on a comparison of the accuracy of the predicted mass flow of the incoming fluid relative to the theoretical value (equal to the inlet volumetric flow rate multiplied by the total elapsed time).

In order to facilitate flexibility in handling the complex geometries in ballast water tanks, an unstructured grid was developed to represent the

Figure �: LIF Images: Flow Through Lighten-ing Hole and Limber Lole at (a) 10 secs and (b) 60 secs.


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physical tank model. A cut plane through the model at the inlet pipe centerline showing the grid structure is given in Figure �. Only the inlet pipe, inlet bellmouth, and exit pipe are modeled using structured hexahedral cells. This is for improved accuracy in predicting the inflow and outflow of the two fluids since the flow direction is mostly aligned vertically. The remainder of the domain volume is discretized using unstruc-tured tetrahedral cells. The grid is also focused in regions of interest, such as near the inlet pipe and inlet bellmouth and through the tank floor openings (e.g., manholes, limberholes) for im-proved resolution. The domain is composed of approximately 1.3 million cells in total.

Validation ResultsThe transient solution of the ballast exchange process was carried out using Fluent. The initial condition was that of quiescent fresh water in the tank. At the start of the simulation, salt water was introduced through the opening at the top of the tank at a flow rate of 65.0 gal/min. The initial time step was 0.025 seconds, and was increased over time as the solution settled into a more stably stratified environment. The simula-tions were carried out until the total elapsed time reached 1050.0 seconds, which corresponds to a total of three complete volume exchanges; one tank volume exchange is equal to the total tank volume divided by the inlet flow rate.

Results from the 1/3-scale model simulations are shown in Figure � at three different elapsed times. Figure 6(a) shows the salt water volume fraction contours on two cut-planes through the inlet and exit pipes after 30 seconds, which corresponds to approximately 10% of one volume exchange. Figure 6(b) corresponds to one complete volume exchange (350 seconds), and Figure 6(c) cor-responds to three complete volume exchanges (1050 seconds). The contour values extend from a saltwater volume fraction of 0.0 (pure fresh-water – shown as red) to 1.0 (pure salt water – shown as blue).

As shown in the figures, early in the ballast exchange process, there is a spreading of the

Figure �: Grid Details in 1/3 Scale Model

Figure �: CFD results: (a) 0.1 volume, (b) 1 volume exchange, (c) 3 volume exchanges.

incoming fluid longitudinally down the tank, as well as over the stringers, which encourages mixing of the two fluids. After one tank volume exchange there is still a significant amount of the

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original fluid left in the tank, trapped between the stringers near the tank top. Negatively buoy-ant jet flows are also seen through the manholes.

After three tank volumes have been completed, there are still some areas of mostly unmixed original fluid trapped between the stringers near the tank top, while in some areas the fluid has become mixed or scoured away. This scenario represents the impact of the tank structure to limit the effectiveness of the exchange process.

For a quantitative comparison, the experimental data in each of the three camera planes was used to determine an average volume fraction over the entire measurement plane. Figure � shows a comparison of the average volume fraction for camera planes 1 (flow over a stringer) and 3 (flow through a manhole and limberhole). As seen in the figure, the CFD model accurately pre-dicts the time at which the saltwater first enters

the camera plane (when the volume fraction first starts to fall from its initial value of 1.0), and captures the trend in the decreasing average volume fraction, though there are some minor discrepancies in the camera 3 plane. This would seem to be due to the CFD model predicting the incoming salt water reaching the measurement plane slightly early and then over-predicting the amount of mixing during the later stages of the exchange.

A comparison of the predicted and measured volume fraction in the camera 3 plane is shown in Figure � at time = 30.0 seconds. The CFD model generally does a good job predicting the negatively buoyant jet flow through the manhole and the mixing layer that develops downstream of the lower limber hole. Similar agreement has been found when comparing the CFD predic-tions with the experimental measurements for the three different camera planes at various times throughout the exchange.

Figure �: Avg. Freshwater Volume Fraction: (a) Camera Plane 1, (b) Camera Plane 3.

Figure �: Volume Fraction in Camera Plane 3 At Time = 30 secs: (a) experiment, (b) CFD.


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Experimental data was also collected to mea-sure the effluent concentration history and the comparison with the CFD model predictions is shown in Figure 9. The experimental data was collected in the exit pipe. In Figure 9 the time scale has been converted to multiples of a single tank volume exchange (t* = tank volume/inlet flow rate), and the effluent concentration is shown in terms of the exchange efficiency, that is the ratio of the total salt water (replacing) fluid to the total volume of the tank. The comparison shows that the Fluent predictions are nearly iden-tical to the experiment up to about t* = 1.2. This is the limit to which the experimental measure-ments could be taken due to facility size (tank storage) limitations. The plot shows every third data point from the experimental measurements.

The discrepancies exhibited in Figures 7 and 8 point out that the flow behavior in the experi-mental model tank is very complex. The pre-dicted overall flow patterns in the tank are not exactly the same as in the experimental model. There are also some three-dimensional effects that are likely to explain some of the differences in the volume fraction contours compared with the LIF images. Based on the results shown in Figure 9, however, it would seem that these do not have a significant impact on the accuracy of the predictions for the overall exchange efficien-cy, which is the primary concern of this study.

The exchange efficiencies are tabulated in table

1. The predicted exchange efficiency after 1 tank volume exchange (t* = 1) is identical to that measured in the experiment. Also, the CFD model predicts that after three volume exchanges have been completed then the exchange efficiency is 0.96, which exceeds the desired 95% threshold.

Full-Scale SimulationsAfter gaining some confidence in the accuracy of the CFD predictions, simulations were also performed for a full-scale tank. A similar grid structure was used, except the full-scale tank also includes upper wing tanks (see Figure 10).

The full-scale tank model is a physical repre-sentation of one of a set of ballast tanks from a typical 35,000 dwt handysize bulk carrier. There are a total of ten rows of double bottom

Figure 9: Exchange Efficiency (1/3-scale)

Table 1: Exchange Efficiencies (1/3-scale)

t* exChange eFFiCienCy CFd exPt 1 0.78 0.78 2 0.92 -- 3 0.96 --

Figure 10: Full-Scale Tank Geometry


tank, hopper side tank, and topside tank bays (see Figure 1 for tank descriptions). The topside tank bays are connected to the hopper tank bays via two connection pipes. The iincoming fluid is pumped into the tank via a single inlet bell-mouth. There are two exits that were modeled as flush with the tank top (not shown) directly above the two connection pipes to simulate an overflow condition. The tank floor openings and stiffeners were modeled based on tank drawings provided by Fednav International.

In order to investigate the influence of the tank structures, two separate grids were developed for the full-scale tank, one with all of the tank structure as shown in Figure 10 and one that ne-glects the reinforcing stringers. The grid that did not include the stringers included approximately 1.3 million cells, while the grid that included the finer structural details required approximately 5.5 million cells. The inclusion of the stringers had a significant impact on the computational resources and time required to perform the simulations. A close-up comparison of the predicted salt water volume fraction in several cut planes near the inlet pipe are shown in Figure 11. In Figure 11(a) the lack of the stiffeners allows the incoming fluid to spread more quickly through the first several tank bays, while in Figure 11(b) the presence of the stiffeners causes the incoming fluid to be trapped at various locations near the inlet. In addition, there are several small-scale mixing events that occur as the salt water is impeded by the structure and then spills over the stiffeners.

The influence of the stiffeners can also be seen in the integral of the volume fraction from the two different grids. Recall that there are two exit locations from the tank, simulating a deck overflow condition directly above the two connection pipes. A comparison of the pre-dicted exchange efficiency for the two different geometries is shown in Figure 1�, and tabulated in table �.

The impact of including the stiffeners is clearly shown in Figure 12. When the stiffeners are neglected, there is significantly less obstruction

Figure 11: Volume Fraction Contours After Time = 60 sec: (a) no stringers, (b) with stringers.

Figure 1�: Exchange Efficiency (full-scale) With and WIthout Stiffeners

Table 2: Exchange Efficiencies (full-scale)

t* exChange eFFiCienCy no StringerS With StringerS theory

1 0.63 0.82 0.63 2 0.81 0.91 0.86 3 0.88 0.93 0.95



to the dispersion of the incoming fluid, and the tank acts more like an open box. A larger amount of the incoming fluid reaches the tank exit much sooner than if the stiffeners were present (see Figure 1�). This causes the effluent concentration history to have a more diffuse profile, closer to that of a perfect mixing scenario, in which the incoming fluid becomes instantaneously mixed with the original fluid, which is not characteristic of the actual flow situation. It is clear that the perfect mixing assumptions are not valid.

Figure 13 also shows a small spike in the effluent concentration for the geometry that includes the stiffeners at around t* = 0.3. This is representa-tive of the mixing event that occurs at the start of the exchange procedure, as the incoming salt water mixes with the fresh water in the inlet bay. After this initial mixing event, the mixed fluid is then transported downstream ahead of the bulk fluid motion. Later in the exchange there is significant mixing that occurs as larger amounts of the incoming fluid passes up through the vertical connection pipes and mixes with the fluid in the upper wing bays. As the amount of incoming fluid passing through the connec-tion pipes increases, the effluent concentration profile reflects the large increase in the amount of incoming fluid that is exiting the tank (around 1 tank volume exchange).

After this, the two fluids become mostly strati-fied in the hopper side bays and the upper wing bays and some of the replaced fluid is trapped in the upper corners of the hopper side bays. From this point, the effluent concentration changes slowly as some of the replaced fluid that is trapped in various parts of the tank due to the tank structure cannot be removed. It is also interesting to note that based on the results of the simulations, this particular ballast water tank does not meet the guidelines for achieving a 95% replacement after three volume exchanges. It is anticipated that this could be improved through structural modifications.

These results would seem to contradict the find-ings of Kent and Parsons (2004) who performed

similar CFD calculations of BWE and concluded that the finer structural details could be neglect-ed and still achieve sufficiently accurate predic-tions of the exchange efficiency. That study, however, was performed with limited computa-tional resources. The predictions of the J-type bottom/side ballast tank, which is a similar tank arrangement to the geometry used in this study, were performed using only 276,000 cells. The assessment of the impact of the finer structural details was not performed on a representative overall tank geometry. Instead, the simulations that included the stringers simply focused on a region of only the double bottom tank bays, which would not account for the mixing that occurs in the hopper tank and topside tank sections where the vertical separations between the structures is also important. Finally, their analyses do not make any comparison with ex-perimental data; hence, it is unclear whether the results are validated.

ConclusionsExperimental and computational fluid dynamics (CFD) methods have been used to examine the flow behavior inside ballast tanks during ballast water exchange (BWE) and to examine the ex-change efficiency. Validation efforts were carried out using an approximately 1/3-scale model of a portion of a typical ballast tank for a bulk car-rier. The results of the validation studies showed excellent agreement between the predicted and measured exchange efficiency.

Figure 1�: Predicted Effluent Concentra-tion (full-scale), With and Without Stiffeners.



Numerical simulations were also performed for a typical full-scale ballast tank in a 35,000 dwt handysize bulk carrier. Two different computational grids were simulated, one of which simplified the geometry by neglecting the reinforcing stiffeners. A comparison of the predicted effluent concentration and exchange efficiency of the two geometries demonstrated significant differences when the stiffeners were neglected. In both cases, the predicted exchange efficiency did not meet the required 95% replacement after three tank volume exchanges for the particular tank geometry that was simulated. It was also clear that perfect mixing assumptions are not valid for exchange efficiency of a real ship tank geometry. It is anticipated that structural modifications would improve the exchange efficiency. The results of the numerical predictions also provide a wealth of information regarding the complex flow behavior inside the tanks. Though not the focus of the present study, the fully three-dimensional flow field information that was gathered during the simulations also points out potential “dead spots” in the tank where local flow velocities are very low and could prove problematic in relation to sedimentation issues.

AcknowledgementsThis project was funded by the National Oce-anic and Atmospheric Administration, Ballast Water Technology Demonstration Program, GLERL Contribution #1371. The authors thank Fednav International for providing the blue-prints of the ballast tank used in the full-scale models. Tom O’Connell (M. Rosenblatt and Son) and Lawrence Tomlinson (NSWCCD) as-sisted with design and operation of the experi-mental model. The authors also thank Dr. Jerry Shan, currently of Rutgers University, for his assistance in conducting the experiments and analyzing the data. ■

Referencesamerican bureau of Shipping, “advisory notes on ballast water exchange procedures,” american bureau of Ship-ping: houston, texas, 23 pp, 1999.

armstrong, g., holdo, a., and a. rose, “an analysis of flow-through ballast water exchange,” international Marine Engineering Transactions 111, Part 2: 59-70, 1999.

atsavapranee, P. and M. gharib, “Structures in stratified plane mixing layers and the effects of cross-shear,” Jour-nal of Fluid Mechanics 342, pp. 53-86, 1997.

drake, l.a.., ruiz, g.M., galil, b.S., Mullady, t.l., Friedman, d.o., and F.C. dobbs, “Microbial ecology of ballast water during a transoceanic voyage and the effects of open-ocean exchange,” Marine ecology-Progress Series, Vol 233, pp1 3-20, 2002.

hay, C. and d. tanis, “Mid-ocean ballast water exchange: procedures, effectiveness, and verification.” a report prepared for the new Zealand Ministry of Fisheries. Cawthron rept no. 468, Cawthron institute, nelson, new Zealand. 46 pp, 1998.

holdo, a., armstrong, g., and a. rose, “an analysis of flow-through ballast water exchange,” international Conference on Marine

engineering Systems/the Society of naval architects and Marine engineers (8th iCMeS/SnaMe), new york, ny, May 2000.

international Maritime organization (iMo), “internation-al Convention for the Control and Management of Ships’ ballast Water and Sediments,” international Maritime organization: london, 2004.

kent, C. and M. Parsons, “Computational Fluid dynam-ics Study of the effectiveness of Flow-through ballast exchange,” transactions of SnaMe, Vol. 112, 2004.

rigby, g., “ocean exchange as a means of mitigating the risks of translocating ballast water organisms - a review of progress ten years down the line.”, J. Mar. Environ. Eng, Vol 6, no. 3, pp 153-173, 2001a.

rigby, g., “ballast water treatment to minimize the risks of introduced nonindigenous marine organisms into australian ports,” ballast Water report #13, dept of agriculture, Fisheries, and Forestry: Canberra, australia. 77 pp, 2001b.

rigby, g. and g. hallegraeff, “the transfer and control of harmful marine organisms in shipping ballast water: be-haviour of marine plankton and ballast water exchange trials on the MV “iron Whyalla”,” J. Marine Env. Eng. 1:91-110, 1994.

U.S. Coast guard, “Standards for living organisms in ship’s ballast water discharged in U.S. waters - advanced notice of proposed rulemaking: request for comments,” Federal register, pp 9632-9638, 2002.


Author BiographiesWESlEy WilSoN is the principal author and is currently an engineer in the Computational Fluid Dynamics group of the Propulsion and Fluid Systems Division at the Naval Sea Systems Com-mand, Warfare Centers, Carderock Division. He received a BS in Engineering-Physics from West Virginia Wesleyan College in 1997 and a MS in Mechanical Engineering from West Virginia Uni-versity in 1999. He began his career and contin-ues to be active in the areas of multiphase flows and droplet dynamics. Current research topics include liquid-liquid mixing, and the transport of non-indigenous species and sediments in bal-last water tanks for commercial shipping vessels. Other areas of focus include the prediction of hydrodynamic forces on submerged bodies and free surface flows around surface ships. He was also a core team member for the NSWCCD Innovation Center Project KAPPA, a concept design for a submersible combatant craft that focused on littoral operations. Mr. Wilson is an associate member of the American Society of Mechanical Engineers.

DR. PEtER CHaNg is currently a naval architect in the CFD group of the Propulsion and Fluid Systems Division at the Naval Sea Systems Command, Warfare Centers, Carderock Divi-sion. He received a B.A. in Applied Mechanics and Engineering Sciences from University of California (UC), San Diego in 1980, a M. Eng. in Naval Architecture and Ofshore Engineer-ing from UC, Berkeley in 1984 and a Ph. D. from the University of Maryland in Mechanical Engineering in 1998. He has been working in the Hydromechanics Directorate of NSWCCD since 1984 where he was first involved with the experimental aspects of surface ship model re-sistance, propulsion and free surface signatures. Since 1990 he has been involved with computa-tional fluid dynamics, performing hydroacoustic research using turbulence simulations; since 1994 Dr. Chang has been deeply immersed in the computational, experimental and practical aspects of compensated fuel/ballast tank and normal ballast tank fluid dynamics. Dr. Chang is a member of ASME and AIAA.

StEPHaN vERoSto is the Uniform National Discharge Standards and NonIndigenous Spe-cies Technical Area Leader for the Naval Sea Systems Command, Warfare Centers, Carderock Division Wastewater Management Branch. He received a BS in Mechanical Engineering in 1991 from the Pennsylvania State University. In 1997 he received a Master of Engineering from the University of Maryland. He began his career at the Naval Ships Systems Engineering Station (NAVSSES) in 1989 where he supported the Combat Support System Repair and Training Program. In 1995 he joined the Environmental Quality Department where he has managed various projects for both the Navy ‘s Shipboard and Shoreside RDT&E programs.

DR. PaiSaN atSavaPRaNEE received his Ph.D. from University of California at San Diego in 1995 in the field of experimental fluid mechanics. He has made significant contributions in the field of turbulent shear flows, bluf body wake dynam-ics, two -phase flows, flows in coastal boundary layers and advanced experimental and optical measurement techniques. Since he joined the Na-val Sea Systems Command, Warfare Centers, Car-derock Division in 2000, he has concentrated his efforts on various high -priority Naval problems such as submarine hydrodynamics, surface-ship seakeeping and Navy environmental issues.

Dr. David F. Reid received a PhD in oceanog-raphy from Texas A&M University in 1979. He has been a research scientist with the federal government since 1969, and since 1985 has worked for the National Oceanic and Atmo-spheric Administration (NOAA) in the Great Lakes. His recent research focus is on aquatic invasive species. He is a member of the NOAA Invasive Species Program Management Team, Director of the NOAA National Center for Research on Aquatic Invasive Species, and Pro-gram/Project Leader or Co-Leader for a number of research projects on the transport of aquatic organisms in ballast tanks of ships.

CaPtaiN PHiliP t. JENkiNS is a British educated and trained Master Mariner whose career in


shipping began as cadet in 1957, and has taken him through command to executive manage-ment in the industry. His consultancy, estab-lished in 1989, focuses specifically on environ-mental stewardship for the marine industry, developing safety, environmental and quality management systems, response plans and audit programs for ship owners and operators in both Canada and the United States. Captain Jenkins has worked extensively on projects to moni-

tor water ballast management and to develop practical alternatives to ballast water exchange. Captain Jenkins serves on the Advisory Com-mittee on ANS to Canada ‘s Commissioner of the Environment and Sustainable Development, and the U.S. National Academies Committee on the St. Lawrence Seaway: Options to Eliminate Introduction of Nonindigenous Species into the Great Lakes.


2007Sa

ve t

he

Da

te DATE »September 18-19

SYMPOSIUM » Fleet Maintenance Symposium 2007

LOCATION »Virginia Beach, VA (with exhibits)

computational and experimental analysis of ballast water exchange

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