|
[Sponsors] |
twoPhaseEulerFoam bubble column crashes due to problems at outlet region |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
March 30, 2015, 07:05 |
twoPhaseEulerFoam bubble column crashes due to problems at outlet region
|
#1 |
Member
Join Date: May 2014
Location: Germany
Posts: 31
Rep Power: 12 |
Hello everyone,
I'm investigating a water air bubble column in a cuboid after Deen. When using more complex modells for the interface momentum transport coefficients I get problems at the outlet area (see pictures below). With SchillerNaumann for drag coefficient everything worked fine, while with IshiiZuber for drag coefficient the simulation crashes. This is my case setup: //========= 1. Mesh =============================// The cuboid measurements are 0.15 m x 0.15 m x 0.45 m. The inlet at the bottom is modelled as rectangular. The water surface is not included. I generated my mesh using blockMesh. It is equidistant. CheckMesh is okay. //========= 2. Boundary conditions ==================// I am using the following boundary condtitions: alpha.air Code:
internalField uniform 0; boundaryField { inlet { type fixedValue; value uniform 1; } outlet { type inletOutlet; phi phi.air; inletValue uniform 0; value uniform 0; } walls { type zeroGradient; } } Code:
internalField uniform (0 0 0); boundaryField { inlet { type fixedValue; value uniform (0 0 0.0784); } outlet { type zeroGradient; } walls { type fixedValue; value uniform (0 0 0); } } Code:
internalField uniform (0 0 0); boundaryField { inlet { type fixedValue; value uniform (0 0 0); } outlet { type slip; } walls { type fixedValue; value uniform (0 0 0); } } Code:
internalField uniform 100000; boundaryField { inlet { type zeroGradient; } outlet { type fixedValue; value $internalField; } walls { type zeroGradient; } } Code:
internalField uniform 1e-4; boundaryField { inlet { type turbulentIntensityKineticEnergyInlet; intensity 0.05; value uniform 0; } outlet { type inletOutlet; phi phi.air; inletValue $internalField; value uniform 0; } walls { type zeroGradient; } } Code:
internalField uniform 1e-5; boundaryField { inlet { type turbulentMixingLengthDissipationRateInlet; mixingLength 1e-3; k k.air; value uniform 0; } outlet { type inletOutlet; phi phi.air; inletValue $internalField; value uniform 0; } walls { type zeroGradient; } } Code:
internalField uniform 1e-5; boundaryField { inlet { type fixedValue; value $internalField; } outlet { type inletOutlet; phi phi.water; inletValue $internalField; value uniform 0; } walls { type zeroGradient; } } I'm assuming a constant air bubble diameter of 4 mm. I only consider drag, lift and virtual mass force. Drag is modelled after Ishii and Zuber as describes here: http://cfd-online.com/Forums/openfoa...eulerfoam.html Lift and virtual mass coefficents are both constant with a value of 0.5. //========= 4. Discretization =======================// Used methods in fvScheme Code:
ddtSchemes { default Euler; } gradSchemes { default Gauss linear; } divSchemes { // from bubble column tutorial default Gauss linear; "div\(phi,alpha.*\)" Gauss vanLeer; "div\(phir,alpha.*\)" Gauss vanLeer "div\(alphaPhi.*,U.*\)" Gauss limitedLinearV 1; "div\(phi.*,U.*\)" Gauss limitedLinearV 1; "div\(alphaPhi.*,.*rho.*\)" Gauss linear; "div\(alphaPhi.*,(h|e).*\)" Gauss limitedLinear 1; "div\(alphaPhi.*,(K.*|p)\)" Gauss limitedLinear 1; "div\(alphaPhi.*,(k|epsilon).*\)" Gauss limitedLinear 1; "div\(phim,(k|epsilon)m\)" Gauss limitedLinear 1; "div\(\(\(alpha.*nuEff.*\)*dev2\(T\(grad\(U.*\)\)\)\)\)" Gauss linear; } laplacianSchemes { default Gauss linear uncorrected; } interpolationSchemes { default linear; } snGradSchemes { default uncorrected; } fluxRequired { default no; p ; } I only use GAMG as suggested by my professor. fvSolution: Code:
solvers { alpha.air { nAlphaCorr 1; nAlphaSubCycles 2; } p { solver GAMG; smoother DIC; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 160; agglomerator faceAreaPair; mergeLevels 2; tolerance 1e-6; relTol 0.0001; } pFinal { $p; relTol 0; } "e.*" { solver GAMG; smoother DILU; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 160; agglomerator faceAreaPair; mergeLevels 2; tolerance 1e-6; relTol 0.0001; } "(k|epsilon|Theta).*" { solver GAMG; smoother DILU; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 160; agglomerator faceAreaPair; mergeLevels 2; tolerance 1e-6; relTol 0.0001; } } PIMPLE { nOuterCorrectors 1; nCorrectors 2; nNonOrthogonalCorrectors 0; residualControl { "(U|k|epsilon)" { relTol 0.0001; tolerance 0.0001; } } turbOnFinalIterOnly off; } relaxationFactors { } //========= 6. Problem ===========================// After air reaches the outlet area it didn't seem to leave. alpha.air gets big (still <1) in the upper cells and the solution eventually crashes shortly after 7.6 s flow. The flow field for U.water shows there is water inflow. I first set up my case using SchillerNaumann for drag and everything worked fine. But using IshiiZuber instead breaks my simulation. I already tried different things that I found on the forum:
Regards, hester Last edited by hester; March 30, 2015 at 08:33. |
|
Tags |
bubble column, twophaseeulerfoam |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Solving bubble column using twoPhaseEulerFoam | vishal3 | OpenFOAM Pre-Processing | 0 | July 11, 2013 06:19 |
Some problems with twoPhaseEulerFoam | su_junwei | OpenFOAM Running, Solving & CFD | 2 | November 2, 2012 01:12 |
ATTENTION! Reliability problems in CFX 5.7 | Joseph | CFX | 14 | April 20, 2010 15:45 |
VOF Outlet boundary condition in cfd - ace | JM | Main CFD Forum | 0 | December 15, 2006 08:07 |
Bubble Column | Glen | Main CFD Forum | 0 | January 24, 2006 00:56 |