openfoam@mimesis - prace training portal: events · mimesis s.r.l. - 26 –28.11.12 hpc enabling of...

Diego Angeli Ph.D

OpenFOAM@mimesis

26 – 28.11.12 HPC enabling of OpenFOAM for CFD applications

mimesis s.r.l. - 26 – 28.11.12 HPC enabling of OpenFOAM for CFD applications - CINECA - Bologna

Acknowledgements

Members of mimesis involved

• Paolo Levoni (CEO)

• Marco Cavazzuti

Collaborators of mimesis

• Elia Agnani

• Stefano Martella

(once were) undergraduate students @UNIMORE

• Ruggero Verzulli

• Federico Rossi


Outline

mimesis introduction

• a road vehicle application

• an agricultural vehicle application

• a fire protection engineering application

Master Thesis Projects @UNIMORE• OpenFOAM vs. Fluent

• aerodynamics of a Formula Student car

OpenFOAM-based industrial research: 3 examples

Education and training

mimesis is an engineering company working in the

fields of thermofluids and energy

“mimesis” means imitation of nature, a nature which

always evolves, improves and refines itself... if the goal

is to optimize, for sure there is no better muse.

mimesis was born as a spinoff company of DIEF

(Dipartimento di Ingegneria “Enzo Ferrari”) from the

Applied Phisics Research Group of the University of

Modena and Reggio Emilia

The company was then expanded in order to

incorporate specific knowledge in the fields of energy

and sustainable mobility, that represent main

challenges for modern human society

energy

thermofluids

thermofluidsservices


design & 3D modelling


CFD thermofluid analyses


standard experimental analysis




advanced experimental analysis






prototype development





optimization processes




CFD thermofluid



optimization processes







servicesenergy

servicesenergy

stationary applications

servicesenergy

energy management and planning


renewable energy plants


servicesenergy


plants and component testing


servicesenergy



development of advanced energy processes and products



servicesenergy




buildings energy diagnosis and plants optimization

servicesenergy





servicesenergy




buildings energy diagnosis and plants optimization



servicesenergy

mobility

servicesenergy

electric prototype development

mobility

servicesenergy


mobility

power supply transformationkits

power supply transformation kits

smart mobility & social pooling


servicesenergy

mobility


smart mobility & social pooling

servicesenergy

power supply transformation kits

mobility


Outline










Road vehicle application

Self-ventilated brake disk for a HP road car



Computational mesh and numerical details

• 36° slice, rotational

symmetry

• flow induced by rotation

• ~1.6 million cells

• hybrid tet-prism mesh

• SRFSimpleFoam

• RANS (k-ω SST)

• I order schemes

• 2 days on an i7 CPU



A snapshot of the results…


Outline










Agricultural vehicle application

Lubrication circuit of a tractor clutch

Cross-section of the whole

clutch group

Reverse gear group

Detail of the reverse gear

group

Main idea:

• 0D approach

• Subparts are represented by

their flow rate/head loss curve

(obtained by OpenFOAM)

• experimental tuning/verification



Subsystem modeling: the friction plates

Metallic disk

Friction material

• the friction plates are made up of a permeable material with many

microchannels, whose full modeling is out of scope

• adoption of a (rotating) porous medium model



A small fix of OpenFOAM development…

• porousSimpleFoam + SRFSimpleFoam = porousSRFSimpleFoam

• Porosity Model: power-law:

• Two coefficients to be tuned

based on experimental data (non-rotating system)

• Extrapolation of the characteristic curve under rotation

21

0

1 /)(C

ii uCS


Outline










• Experiments were performed for the case of a heptane pool fire in a full-

scale under-ventilated environment (a closed garage), measuring the

temperature at several locations by the use of thermocouples

• The experimental layout has been numerically reproduced and simulated

using fireFoam

• This is a preliminary study in order to validate the CFD solver and

understand the critical issues in fire modelling

• The work is still in progress and the numerical model still has to be

calibrated properly, just a quick overwiev on the problem and the results

obtained so far will be given

Fire Safety Engineering Application

Numerical validation of the OpenFOAM-based CFD solver fireFoam



Experimental room and thermocouples layout: front view and top view



Experimental room and thermocouples layout: front view and top view

• A steel panel is located 1m above the

pool fire

• Thermocouples were mainly located

on the central x-z plane at different

heights, at the wall, at the room

centre, and on the right of the steel

panel

• Temperatures were recorded every

11s


• Inlet BC: the fuel burning rate of a pool fire is not known a priori and must

be set according to experimental results

• Wall BC: a 3rd type (wallHeatTransfer) condition is applied, however a

global wall heat transfer coefficient is not known from experiments

• Outlet BC: two thin outlet sections are added to the numerical model in

correspondence to the garage door in order to avoid the pressurization of

the room

• In strongly under-ventilated conditions such as the one we are addressing

fuel combustion is incomplete and a lot of soot is produced, thus the actual

Heat Release Rate of the fuel is not known a priori; as a first guess it is

assumed a combustion efficiency of 75% both in terms of fully burnt fuel

mass and HRR: the following combustion reaction is adopted

C7H

16+ 11O

2+ 37.27 N

25CO

2+ 2CO + 8H

2O + 37.27N

2+ 34MJ/kg


Numerical setup: BCs and critical issues



Fire evolution: experiment vs simulation



Temperature history at various locations


Outline










MS Projects – OpenFOAM vs. Fluent

Test case n.1 – hydrodynamics of appendages

3 turbulence models:

• Spalart-Allmaras

• SST k-ω

• RSM *(I order)

Simulation types:

• simpleFoam

• RANS

• II order schemes*




FluentOpenFOAM

k-ω SST model: qualitative comparison




FluentOpenFOAM

Spalart-allmaras model: qualitative comparison




RSM model: quantitative comparison



Test case n.2 – Wigley-Hull

Simulation types:

• interFoam

• RANS (k-ω SST)

• II order schemes



Test case n.2 – Wigley-Hull

FluentOpenFOAM FluentOpenFOAM

pressure distribution on

the free surface

free surface

relative height


Outline










MS Projects – Formula Student

External aerodynamics study of the UNIMORE 2012 IMechE Formula Student single-seater


Outline










• Since 2010, we teach an introductory course on OpenFOAM (20 hrs. +

project work) to the Undergraduate Master Students of Mechanical

Engineering and Vehicle Engineering, in the frame of the Numerical

Thermofluid-dynamics course


Education @ DIEF - UNIMORE

• We held a small “crash course” on OpenFOAM at the 12th U.I.T. Summer

School (organized by the Italian Union of Thermofluid-dynamics, Sep. 2012)

• We are looking forward to organizing on-demand courses for industry

researchers and/or to partnering existing training events (no community, no OF!)

Training

mimesis s.r.l. - c/o DIEF Dipartimento Ingegneria “Enzo Ferrari” - via Vignolese 905, 41125 Modena

CFD analysis of theMont Blanc Tunnel

26 – 28.11.12 HPC enabling of OpenFOAM for CFD applications

Diego Angeli, Ph.D


• Collaboration among DIEF, Mimesis s.r.l. and GEIE-TMB started in 2009, on

the study and optimization of the Mont Blanc tunnel ventilation system.

• The research is carried out by both modeling and experiments, combined in

an integrated approach for the analysis of this class of problems.

• Experiments allowed to collect accurate in situ air velocity data for model

development and validation, and for the verification of airflow control

infrastructures.

• Numerical work:

• 3D full-scale CFD with OpenFOAM

• development of 1D codes for simplified modeling

Overview

The project


Experimental work

Like moles in a wormhole…


Huge domain

Full-scale simulation

Critical aspects

Length 11611 m

Height 6 m

Width 9 m


Huge domain

Ventilation elements


Critical aspects

Jet fans

Fresh air intake

Smoke extraction outlet


Ventilation elements


Critical aspects

Huge domain

Complex modularity


TMB Modeling

Geometrical simplifications

Typical tunnel section

No garages

No sidewalk

No road signs

Equivalent wall roughness

(tuned with experimental data)


TMB Modeling



Modeling of small air vents

(one each 10 m) avoided

Continuous boundary patch

Fresh air intake


Fresh air intake

TMB Modeling



Internal machinery unmodeled

Hollow cylinders with ad-hoc BCs

Jet fans


TMB Modeling

Meshing

Optimal section grid

Mesh convergence

assessed by means of

Richardson analysis


Axial refinement

TMB Modeling

Meshing

Optimal section grid

Near high-gradient zones

• Smoke extraction

• Jet fans

• Fresh air intake


Jet fans modeling

Modeling procedure

Experimental

characterization

Hot-wire anemometry

Measurement if Ur, Uϑ, Uz

and k


Jet fans modeling

Modeling procedure

Experimental

characterization

Curve fits of

experimental data

Ensure mass conservation

Swirl taken into account


Customized BC

Jet fans modeling

Modeling procedure

Experimental

characterization

Available fanPressureBC

• No mass conservation

• No swirl

Curve fits of

experimental data


At the fan suction inlet (an outlet of the CFD model), pressure is imposed as

equal to the average pressure at the discharge section, minus the nominal

pressure jump given by the fan; a zero gradient condition is imposed for the

velocity

TMB Modeling

Customized BC for jet fans

0=Δ=S

FANDS nppp

∂

∂-

u

At the fan discharge (an inlet of the CFD model), velocity is imposed as

equal to the average velocity at the suction, multiplied by the reconstructed

dimensionless velocity profile (ensuring mass conservation); a zero gradient

condition is imposed on pressure

0=~•=D

DSD n

pU

∂

∂uu


Jet fans modeling

Application of customized BC

Swirl


Jet fans modeling


Swirl

Coanda effect


Jet fans modeling


Coanda effect

Swirl

Validation vs. experimental data

n. fans 1 2 3

Uexp

[m/s] 3.10 3.21 3.17

UOF

[m/s] 3.19 3.36 3.35

E % 2.8 4.5 5.8


~2 million cells

k- realizable model,

standard wall functions

All ventilation elements in

a 300 m long tunnel

segment

Trouble-free calculation


Towards the complete TMB simulation

Qualitative analysis

of a tunnel segment





of a tunnel segment

Decomposition in elemental

blocks

Arbitrary Mesh Interface (AMI)

Control scripts

How to build the

whole model?


How to build the

whole model?




of a tunnel segment

Full-scale simulation @ CINECA

Multiscale coupling with 1D

models

Perspectives

www.mimesis.eu [email protected]

o c/o DIEF - Dipartimento di Ingegneria “Enzo Ferrari”

Via Vignolese 905, 41125 Modena - IT +39 3394307873

o spanish office

Calle Ortigosa 14, 08003 Barcelona - ES +34 654850706

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