Computational Directions in Mechanical Engineering at The University of Alabama

Will SchreiberKeith Woodbury

Overview

•Inverse Problems and Optimization in Heat Transfer–Keith Woodbury

•Heat Transfer

•IC Engines–Will Schreiber

Inverse Problems and Optimization in Heat Transfer

Keith A. WoodburyMechanical EngineeringUniversity of Alabama

What are inverse problems?

•An Inverse Problem is one of determining unknown causes on the basis of observed effects

•Contrast with a Direct Problem of computing system responses based on specified inputs

Classes of Inverse Problems

•Inverse Boundary Problem–Determine unknown action at a

physical boundary; typically a function of time

•Inverse Coefficient Problem–Determine unknown coefficients, such

as thermophysical properties

General Approach•Combine

–Model •Complete mathematical description of physics, usually

heat conduction process

–Data•Measured temperature histories at one or more locations

in the domain

–Fitness Measure•Quantify discrepancy between model and data, usually

with sum-squared error

–Minimization Technique

Numerical Modelswe use…

•Finite element methods are our primary choice–Custom codes for inverse problems

–Commercial package FIDAP used for routine simulations

Minimization Techniques we have used…

•Sequential Function Specification Method (a.k.a. Beck’s method)

•Gradient Methods (a.k.a. Adjoint Method)

•Evolutionary Algorithms (a.k.a. Genetic Algorithms)

•Neural Networks

Projects

•Identification of thermal contact resistance in sand castings–American Foundryman’s Society and

DOE 0.25" Horizontal Plates (Tops) 07/29/98 + 07/30/98 + 08/12/98 + 08/24/98

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hc,

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073098a

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072998corra

Projects

•Toward Improved Al-Be Castings–NASA – thru Auburn University

Projects

•Design and CFD Analysis of Water/Fuel Evaporator for Fuel Cell Reformer–Ballard Corporation / TACOM

Selected Publications…

• Pohanka, M., and Woodbury, K. A., “A Downhill Simplex Method for Computation of Interfacial Heat Transfer Coefficients in Alloy Casting,” Inverse Problems in Engineering, to appear 2003.

• Woodbury, K. A., Woolley, J. W., Piwonka, T. S., and Pohanka, M., “Metal/Mold and Mold/Environment Interfacial Heat Transfer Coefficients in Active and Passive Cooling of Investment Castings,” AFS Transactions, Vol. 111, 03-114, 2003, pp. 1-13

• Krejsa, J., Woodbury, K. A., Ratliff, J. D., and Raudensky, M., “Assessment of Strategies and Potential for Neural Networks in the IHCP,” Inverse Problems in Engineering, Vol 7, n 3, 1999, pp. 197-213.

• Beck, J. V., and Woodbury, K. A., “Inverse Problems and Parameter Estimation: Integration of Measurements and Analysis,” Measurement Science and Technology, Vol. 9, no. 6, June, 1998, pp. 839-847.

Selected Publications…

• Woodbury, K. A., “Application of Genetic Algorithms and Neural Networks to the Solution of Inverse Heat Conduction Problems: A Tutorial,” 4th International Conference on Inverse Problems in Engineering, May, 2002, Angra dos Reis, BRAZIL

• Woodbury, K. A., and Ke, Q., “A boundary Inverse Heat Conduction Problem with phase change for moisture-bearing porous medium,” Third International Conference on Inverse Problems in Engineering, Port Ludlow, WA, June 13-18, 1999, pp. 363-369

• Woodbury, Keith A., Krishnamurthy, S., and Durrans, S. Rocky, “Solution of a Non-Linear Inverse Problem in Open Channel Flow by Mollification and Space Marching,'' ASME Proceedings of the 32nd National Heat Transfer Conference Volume 2, HTD Vol. 340, ASME/AIChE 1997 National Heat Transfer Conference, August, 1997, pp. 69-74.

Selected Publications…

• Woodbury, K. A., and Boohaker, C. G., “Simultaneous Determination of Temperature-Dependent Thermal Conductivity and Volumetric Specific Heat,'' HTD Vol. 332, 1996 ASME IMECE, pp. 269-274.

• Woodbury, K. A., and Premanand B., “Finite Element Solution of the 2D-IHCP: Application to Steady-State Problems,” Second International Conference on Inverse Problems in Engineering, Engineering Foundation, June 9-14, 1996, Le Croisic, France. pp 499-504.

• Woodbury, K. A., and Jin, X., “A Temperature-Based Sequential Function Specification Method for the IHCP,” HTD Vol. 312, 1995 National Heat Transfer Conference, Portland, OR, August 1995, pp. 141-150.

IC Engines

Will SchreiberMechanical EngineeringUniversity of Alabama

Computational Methodologies Used to Study Combustion in IC

Engines• Phenomenological

model of Diesel fuel jet developed on principle of packets

• Phenomenological model of Diesel fuel jet currently under development based on analytical and numerical principles

Computational Methodologies Used to Study Combustion in IC

Engines•Three-

dimensional fluid flow solvers (KIVA and FIDAP)

•Adaptive meshes

•Experimental study of jets for validation

Recent Projects in IC Engines

•Optimization of Diesel for lowering emissions using AGI and EGR

•Study of effect of O2 enriched air on Diesel emissions

•Effect of EGR and split fuel injection on Diesel emissions

•Development of fuel jet combustion model using a combination of analytical and numerical methods.

Recent Publications Concerning IC Engines

• Schreiber, W., 2003, “A Mathematical Model for Predicting Scalar Transport in a Transient Incompressible Jet”, 3rd Joint Meeting of the U.S. Sections of The Combustion Institute, Chicago, IL, March 16 – 19, 2003, paper E20.

• Gao, Z., and Schreiber, W., 2001a, “A Phenomenologically Based Computer Model To Predict Soot And Nox Emission In A Direct Injection Engine”, International Journal of Engine Research, Vol. 3, pp. 177 – 188.

• Gao, Z., and Schreiber, W., 2001b, “The Effects Of EGR And Split Fuel Injection On Diesel Engine Emission”, International Journal of Automotive Technology, Vol. 2, pp. 123 – 133.

Recent Publications Concerning IC Engines

• Gao, Z., and Schreiber, W., 2002 “A Theoretical Investigation of Two Possible Modifications to Reduce Pollutant Emissions from a Diesel Engine”, Journal of Automotive Engineering, in review.

• Gao, Z., and Schreiber, W., “A Multizone Analysis of Soot Emission in a D.I. Diesel Engine as a Function of Engine Load, Wall Temperature, and Intake Air O2 Content”, 2000 Fall Technical Conference, Proceedings ASME, ICE Division , Section VII_paper 4, September 24-27, 2000.

• Gao, Z., and Schreiber, W., “The Use of a Multi-zone Model for Prediction of Soot Emission in a D.I. Diesel Engine as a Function of Intake Air O2 Content”, The 2000 International Mechanical Engineering Congress & Exposition November 5-10, 2000, Orlando, Florida HTD-Vol 366-5. pp. 95 – 103.

Other Heat Transfer Projects

•Simulation of boiling heat transfer

•Solidification of binary fluids

•Thermal ground water simulation for environmental flows

AGI Used to Lower Soot and NOx