|
[Sponsors] |
Setting up boundary conditions for chtMultiRegionSimpleFoam |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
July 31, 2016, 20:34 |
Setting up boundary conditions for chtMultiRegionSimpleFoam
|
#1 |
New Member
Join Date: Jun 2016
Posts: 6
Rep Power: 9 |
Hello, I want to simulate a egr cooler and i have trouble with the region of the water. I get unrealistic results for the temperature and the simulation crashes. I think i made a mistake with the boundary conditions.
For U: Code:
water_inlet { type flowRateInletVelocity; massFlowRate constant 0.967222; //=3480kg/h rho rho; rhoInlet 1000; } water_outlet { type inletOutlet; value uniform ( -0.01 0 0 ); //unsure of the value. Had only the mass flow inletValue uniform ( 0 0 0 ); } "water_wall.*" { type fixedValue; value uniform (0 0 0); } Code:
water_inlet { type fixedValue; value uniform 358.65; } water_outlet { type inletOutlet; value uniform 360.55; inletValue uniform 360.55; } water_wall_to_solid { type compressible::turbulentTemperatureCoupledBaffleMixed; value uniform 360; Tnbr T; kappa fluidThermo; kappaName none; } water_wall_adiabat { type zeroGradient; value uniform 360; } Code:
"water_wall.*" { type zeroGradient; value uniform 1000; } water_inlet { type zeroGradient; value uniform 1000; } water_outlet { type fixedValue; value uniform 1000; } Code:
water_inlet { type fixedValue; value uniform 0.01; } water_outlet { type inletOutlet; inletValue uniform 0.01; value uniform 0.01; } "water_wall.*" { type compressible::kqRWallFunction; value uniform 0.1; } Code:
--> FOAM FATAL ERROR: Maximum number of iterations exceeded Last edited by astronauti; August 2, 2016 at 05:57. |
|
August 1, 2016, 09:45 |
|
#2 |
Senior Member
Join Date: Sep 2013
Posts: 353
Rep Power: 20 |
For p your boundary should be calculated on all patches. For p_rgh you could switch to fixedFluxPressure on walls. But boundary conditions are often not the problem. cht simulations are easy to crash or get wrong. In most cases your mesh is just not good enough. Even if checkMesh does not yet complain. If your mesh is of good quality you can check your schemes. Start with upwind if possible. Another way to get better results is to initialize the velocities without solving the temperature. All of this depends on your flow conditions/turbulence model etc. For industrial cases kOmega might be more stable....You might want to try turning turbulence modeling of to see if this is the problem....there are to many options for this kind of error message.
The easiest way to test your boundaries is a test case. Check your boundary conditions on a simple duct or something like it. This way the mesh won't be an issue and you can easily see if the results are reasonable |
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Velocity vector in impeller passage | ngoc_tran_bao | CFX | 24 | May 3, 2016 21:16 |
Difficulty In Setting Boundary Conditions | Moinul Haque | CFX | 4 | November 25, 2014 17:30 |
Setting rotating frame of referece. | RPFigueiredo | CFX | 3 | October 28, 2014 04:59 |
Water subcooled boiling | Attesz | CFX | 7 | January 5, 2013 03:32 |
A problem about setting boundary conditions | lyang | Main CFD Forum | 0 | September 19, 1999 18:29 |