Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Implementation of multiple deltaTs for the multi-region solver based on chtMultiRegionFoam Yuzhu Pearl Li Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, Stavanger, Norway 2016-12-5 Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 1 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Outline Outline This work is to demonstrate the structure of chtMultiRegionFoam solver in FOAM-extend-4.0 and to implement modifications upon it. Introduction A walk through the solvers Multi-region loop modifications Verification: Try with the new solver Pressure coupled boundary condition Summary and future work Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 2 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Introduction Introduction Multi-physics(multi-region) problems chtMultiRegionFoam Solver modifications *Note that the chtMultiRegionFoam in Foam-extend-4.0 has differences from the version in OpenFOAM-4.0. This work may not be able to directly applied to other OpenFOAM versions. Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 3 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Multi-physics(multi-region) problems Multi-physics(multi-region) problems Wave-Structure-Soil Conjugate Heat Transfer Interaction A multi-physics problem has multiple physical domains; the interaction between the domains are achieved by boundary condition update. For some multi-physics problems, it is not efficient to calculate the multiple regions with the same mesh size and time step. Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 4 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Multi-physics(multi-region) problems Conjugate heat transfer and wave-structure-soil interaction The modification of the chtMultiRegionFoam is regarded as an initial step to develop a wave-structure-soil (WSS) interaction solver. chtMultiRegionFoam: heat transfer (Kappa, T) between fluid and solid regions. Wave-structure-soil Interaction: pressure transfer (p) from fluid to solid regions. Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 5 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and chtMultiRegionFoam chtMultiRegionFoam What and why? The chtMultiRegionFoam is a multi-regional(multi-physics) solver working on fluid and solid regions. The chtMultiRegionFoam contains solvers for each domain and they are coupled by boundary condition update. The physical feature of the conjugate heat transfer is one-way coupling, from the high temperature regions to the low temperature regions. The chtMultiRegionFoam is a transient solver (while chtMultiRegionSimpleFoam is a steady-state solver). Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 6 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Solver modifications Solver modifications Based on chtMultiRegionFoam , Loop modification with multiple deltaTs (two approaches) Solver verifications by case study Pressure coupled boundary condition Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 7 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and A walk through the chtMultiRegionFoam solver |----- chtMultiRegionFoam.C |----- fluid | |----- ... | |----- solveFluid.H |----- solid |----- ... |----- solveSolid.H |----- derivedFvPatchFields | |----- solidWallHeatFluxTemperature | |----- solidWallMixedTemperatureCoupled |----- regionProperties |----- include |----- readPIMPLEControls.H |----- Make Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 8 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and A walk through the chtMultiRegionFoam solver chtMultiRegionFoam.C , the main source file, calls the needed files and solvers. regionProperties/ reads fluid and solid region names setted in the constant/regionProperties of the case files. fluid/ contains source files that solve equations forcontinuity momentum, enthalpy, pressure for the fluid regions. solid/ contains source files for solving heat conduction equation in solid regions. derivedFvPatchFields/ contains files that set new boundary conditions for the coupling between solid and fluid domains. include/ contains files to set/reset the multi-region time step. Make/ contains files for compilation purpose. Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 9 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and chtMultiRegionFoam.C chtMultiRegionFoam.C The source file of chtMultiRegionFoam.C provides a main clue of how is the solver constructed. It can be viewed by f40NR cd $FOAM_SOLVERS/heatTransfer/chtMultiRegionFoam vi chtMultiRegionFoam.C Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 10 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and PIMPLE loop The PIMPLE loop in chtMultiRegionFoam.C for (int oCorr=0; oCorr<nOuterCorr; oCorr++) { forAll(fluidRegions, i) { Info<< "\nSolving for fluid region " << fluidRegions[i].name() << endl; #include "setRegionFluidFields.H" #include "readFluidMultiRegionPIMPLEControls.H" #include "solveFluid.H" } forAll(solidRegions, i) { Info<< "\nSolving for solid region " << solidRegions[i].name() << endl; #include "setRegionSolidFields.H" #include "readSolidMultiRegionPIMPLEControls.H" #include "solveSolid.H" } } Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 11 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and PIMPLE loop PIMPLE loop The chtMultiRegionFoam solver uses PIMPLE loop algorithm. PIMPLE algorithm is a combination of the pressure-implicit split-operator (PISO) and the semi-implicit method for pressure-linked equations (SIMPLE) algorithms. The PIMPLE parameters are set in the fvSolution in a case. For example, PIMPLE { momentumPredictor off; nOuterCorrectors 1; nCorrectors 2; nNonOrthogonalCorrectors 1; pRefCell 0; pRefValue 0; } Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 12 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Fluid solver and solid solver Fluid solver The fluid solver solves: density rho pressure p , the derivative of pressure DpDt velocity U thermal energy h h = c p · dT (1) where c p is the specific heat capacity at a constant pressure. Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 13 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Fluid solver and solid solver Fluid solver includes four equations: solveFluid.H if (oCorr == 0) { #include "rhoEqn.H" //Solve the continuity for density. } #include "UEqn.H" //Solve the momentum equation #include "hEqn.H" //Solve the thermal energy // --- PISO loop for (int corr = 0; corr < nCorr; corr++) { #include "pEqn.H" //solve pressure } turb.correct(); rho = thermo.rho(); Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 14 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Fluid solver and solid solver Solid solver The solid solver solvers temperature T . Variables that are needed for solving the temperature equation are: thermal conductivity ( Kappa ) specific heat capacity ( cp ) solid density ( rho ) Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 15 / 38
Outline Introduction The chtMultiRegionFoam solver Loop modification Test the new solver Pressure coupled B.C. Summary and Fluid solver and solid solver Solid solver The solid solver solves the TEqn for solid regions. tmp<fvScalarMatrix> TEqn ( fvm::ddt(rho*cp, T) - fvm::laplacian(Kappa, T) ); TEqn().relax(); TEqn().solve(); } The corresponding mathematical formula for the TEqn is: ∂T ρ · c p ∂t − ∇ ( KT ) = 0 (2) where K denotes Kappa . Yuzhu Pearl Li Implementation of multiple deltaTs based on chtMultiRegionFoam 2016-12-5 16 / 38
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