WP1: Multiphase modelling with overset mesh · WP1: Multiphase modelling with overset mesh ZhihuaMa,LingQian,DerekCauson,CliveMingham, andPedroMartínezFerrer Centre for Mathematical

BackgroundDevelopment of overset mesh CFD solver in OpenFOAM

Preliminary resultsConclusions & future work

WP1: Multiphase modelling with overset mesh

Zhihua Ma, Ling Qian, Derek Causon, Clive Mingham,and Pedro Martínez Ferrer

Centre for Mathematical Modelling and Flow AnalysisThe Manchester Metropolitan University

2016-06-06

Ma, Qian, Causon, Mingham & Ferrer CMMFA – MMU 1/23



Outline

1 BackgroundLaunch and Recovery OperationsOpenFOAM and dynamic meshOverset mesh method (OGM)

2 Development of overset mesh CFD solver in OpenFOAMThe overall strategyogFoam: a multiphase overset mesh modelling tool

3 Preliminary resultsDambreakWave tankWedge

4 Conclusions & future workConclusions




Launch and Recovery OperationsOpenFOAM and dynamic meshOverset mesh method (OGM)

Launch and Recovery Operations

Rescue and recoveryChallenges

High sea statesModelling tool

accuratefast

Risk predictioncollisionunacceptablemotions

Testingnew concept andsystem





OpenFOAM

Framework

Open sourcePack: single/multiphase flowmodellingLanguage: C++Parallelisation: MPIin/compressible air andwaterVolume of fluid method

Meshing

Static meshDynamic mesh

dynamic mesh refinementdynamic deforming mesharbitrary mesh interface(turbomachinery)

Limitationsmesh qualityamplitude of motion





Dynamic deforming mesh

The main issues with dynamic deforming mesh are mesh quality aswell as limited amplitude of motion.





Overset mesh method

Start: Late 1970s and 1980s, Joseph Steger, NASA AMES

Steger JL, Dougherty FC, Benek JA. A Chimera gridscheme. In: Ghia KN, Ghia U, editors. Advances in gridgeneration. ASME FED-Vol. 5, 1983.

Original concepts of OGMTo model multi-component systems where an optimumbody-fitted grid is used for each component




The overall strategyogFoam: a multiphase overset mesh modelling tool

Zonal approach for L and R

7

e of this research and following industrial partners’ suggestions, the new tool will

odel. However, the velocity potential needed for the QALE-FEM will velocity he multi-s zero in non-zero d so the ocity and on differ- region. ues will ored to ing be- in the

, QALE-e steps o max- e NS

NS

FNPT

Larger vessel

Smaller vessel

Inner domain

Outer domain

Meshes for larger and small vessels are generated independentlythen assembled together. The small mesh surrounding the smallvessel moves with the vessel (6DoF), the big mesh could move withthe large vessel or stay stationary.





Basic steps of OGM

1 Mesh generation: component grids are generated in a(virtually) independent manner.

2 Domain connectivity information (DCI):Hole cutting: blank out the mesh cells out of flow domain.Locate the fringe points and seek interpolation stencils (onother meshes).Orphan point: a proper interpolation stencil cannot beestablished.

3 Flow information exchange: the information at a fringe pointis interpolated from its supporting stencil.

4 Solve the flow on the filed points/cells, update the flow.5 Repeat steps 2 to 4 for deforming/moving boundary problems.





wsiFoam

A multi-region two-phase flow solver for wave-structureinteractions.

Coupling of incompressible and compressible two-phaseNavier-Stokes solvers.Coupling of single-phase potential flow and two-phase NSsolvers.Wave generation:

Velocity profileWave paddle: piston, plunger, flap

6DoF:Dynamic deforming meshArbitrary mesh interface





ogFoam

On top of wsiFoam and enhanced with overset mesh capability:Hole cuttingDCI informationData interpolation

int main(int argc, char *argv[]){

...//load meshes and initialise flow regions

//cut hole#include "holeCutInterFoam.H"

//set DCI#include "dciInterFoam.H"

...while (runTime.run()){

...//- PIMPLE loop over the regionsfor (int oCorr=0; oCorr<nOuterCorrMultiRegion; oCorr++){

//Interpolate information for fringe cells#include "interFringeInterFoam.H"

//solve the incompressible region

//solve the compressible region...

}

runTime.write();

Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"<< " ClockTime = " << runTime.elapsedClockTime() << " s"<< nl << endl;

}

Info<< "End\n" << endl;

return 0;}




DambreakWave tankWedge

Dambreak-1

The red and green lines represent the free surface obtained onoverset meshes and a single-block mesh. The white lines illustratethe pressure contour lines on the two overset meshes.





Dambreak-2

Comparison of the overset mesh solution and the single-block-meshsolution. The red and green lines represent the free surfaceobtained on overset meshes and a single-block mesh.





Wave tank

Tank size: 320 m × 55 m; Water depth: 30 m; Wave height: 5 m.Wave Period: 10 s. Comparison of the overset mesh solution andthe single-block-mesh solution. Red and blue colours indicate thediscrepancy between the two solutions.





Wave tank

-1.5

-1

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0.5

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0 20 40 60 80 100

Wave e

levati

on (

m)

Time (s)

Wave gauge at x=10 m

interFoamogFoam-zeroGradient

ogFoam-mapped

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Wave e

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ogFoam-mapped

Figure 1: Comparison of the overset mesh solutions and the single-blockmesh results.





Wave tank

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-1

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Wave e

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ogFoam-mapped

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Wave e

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ogFoam-mapped

Figure 2: Comparison of the overset mesh solution and the single-blockmesh results.





Wave tank

-1.5

-1

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Wave e

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ogFoam-mapped

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Wave e

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ogFoam-mapped

Figure 3: Comparison of the overset mesh solutions and the single-blockmesh results.





Wave tank

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-1

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0 20 40 60 80 100

Wave e

levati

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Time (s)


reference waveshort-error-zeroGradientshort-error-mappedlong-error-zeroGradient

-1.5

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Wave e

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Figure 4: Discrepancies between the overset mesh solutions and thesingle-block mesh results.





Wave tank

-1.5

-1

-0.5

0

0.5

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0 20 40 60 80 100

Wave e

levati

on (

m)

Time (s)



-1.5

-1

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0 20 40 60 80 100

Wave e

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m)

Time (s)








Wave tank

-1.5

-1

-0.5

0

0.5

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0 20 40 60 80 100

Wave e

levati

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m)

Time (s)



-1.5

-1

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0

0.5

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1.5

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0 20 40 60 80 100

Wave e

levati

on (

m)

Time (s)








Oscillating wedge

The wedge oscillates in the vertical direction with a sinusoidal lawy = A sin(ωt).





Freefall of a wedge

The wedge falls freely under gravity.




Conclusions

Conclusions

An accurate and fast modelling tool is a necessity to predictrisks and to facilitate testing for launch and recoveryoperations at high sea states.Dynamic deforming mesh method has limitations in dealingwith the large amplitude of structure motion and mesh quality.A multiphase overset mesh modelling tool is being developedwithin the framework of OpenFOAM. Preliminary results havebeen produced and presented for several test cases. The toolshows its advantages in dealing with relatively large amplitudeof structure motion.Next step’s work will focus on the improvement ofhole-cutting, information interpolation, parallelisation of thenumerical tool and further extension to handle L and Roperations.




Conclusions

Thank you


Documents

WP1: Multiphase modelling with overset mesh · WP1: Multiphase modelling with overset mesh ZhihuaMa,LingQian,DerekCauson,CliveMingham, andPedroMartínezFerrer Centre for Mathematical