View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0002236 | OpenFOAM | Bug | public | 2016-09-06 07:28 | 2016-09-07 15:21 |
| Reporter | TomasR | Assigned To | henry | ||
| Priority | high | Severity | major | Reproducibility | always |
| Status | resolved | Resolution | fixed | ||
| Platform | Unix | OS | Ubuntu | OS Version | 16.04 |
| Summary | 0002236: Compute crash when z coordinate is higher in interFoam | ||||
| Description | I have two identical models, one has min. elevation of bottom at coordinate z = 0, another at z = 100. Water should flow from inflow to outflow, inflow has water level 0,4 m higher than outflow. I would like to have a fixed water levels and evaluate U and flowrate of water, the behavior of air is not important for me so I divided inflow and outflow faces to two which one is patch, second wall. Top is atmosphere. So I have a boundary conditions: inlet: alpha - fixedValue, value uniform 1 p_rgh - fixedValue, value uniform rho(water)*g*zcoord_of_waterlevel_at_inlet U - outletInlet, outletValue uniform (0 0 0) (I don't expect back flow) outlet: alpha - inletOutlet, inletValue uniform 1 p_rgh - fixedValue, value uniform rho(water)*g*zcoord_of_waterlevel_at_outlet U - zeroGradient (if there could be back flow) atmosphere: alpha - inletOutlet, inletValue uniform 0 p_rgh - totalPressure, p0 rho(air)*g*zcoord_of_patch U - pressureInletOutletVelocity other faces are walls. The model with bottom situated at z=0 run well. The model with bottom at z=100 crashes but at pathes are the prediscribe conditions. Inside of model appears a locations with high negative pressure and than compute crash or not convergate. I also tried to add a pRefValue and pRefPoint do PIMPLE in fvSolution but with no success. | ||||
| Steps To Reproduce | blockMesh setFields interFoam | ||||
| Tags | interFoam | ||||
|
|
|
|
|
I tried to do the same with tutorial weirOverflow and also there occur a problem with model with baseplane higher (y = 100 in my example). At inlet patch a higher water level appears then in internal it drop to normal. Model with baseline near 0 run correct. I would like to use interFoam to compute flux at high structures (up to just 100 m), so I'm affraid about precision. I hope that I make somewhere mistake but where... |
|
|
The weirOverflow tutorial is currently setup for the lowerWall to be at y=0, to run it at a different height you will need to use the fixedFluxPressure BC for p_rgh: lowerWall { type fixedFluxPressure; } I will update the tutorial in 4.x and dev to avoid this confusion in the future. |
|
|
The inlet perturbation relates to the upperBound set in the alpha.water file, if you set it to 1: inlet { type variableHeightFlowRate; lowerBound 0; upperBound 1; value uniform 0; } the inlet behavior is better. I will test the standard tutorial setup and if it runs OK with 1 for upperBound I will make that the default. |
|
|
One more thing, in order to get the same results with an off-set on height of 100m you need to use a tighter tolerance when solving for p_rgh due to the loss of precision from the rho*g*h off-set. |
|
|
Excuse me, do you mean solver tolerance or relTol? At first sight I guess it could be the relTol...default set is 0,05 for p_rgh so is it mean that for 100m off-set and water is 100*9,81*1000*0,05 = 49050 Pa so it is 5 m of water column tolerance? The tolerance is default 1e-7, it means absolute tolerance with 0,0000001 precision? When the solver use relTol and tolerance? |
|
|
I reduced both the tolerance and the relTol in my tests to check that I then get the same results with and without the 100m offset. I did not check if both changes are required, I would expect that a reduction in tolerance only should be sufficient. |
|
|
I make a test and in my test is relTol limiting. Also upperBound 1 in variableHeightFlowRate is better. Thank you. |
|
|
Resolved in OpenFOAM-dev by commit 7b971a9ebf1e53483f1cfa88470e88978f917d3d Resolved in OpenFOAM-4.x by commit 8efaef8c300a575ba01943cffba45172df279eea |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2016-09-06 07:28 | TomasR | New Issue | |
| 2016-09-06 07:28 | TomasR | File Added: TESTINTERFOAM.7z | |
| 2016-09-06 07:28 | TomasR | Tag Attached: interFoam | |
| 2016-09-07 13:09 | TomasR | File Added: weirOverflow100.7z | |
| 2016-09-07 13:09 | TomasR | Note Added: 0006840 | |
| 2016-09-07 13:38 | henry | Note Added: 0006841 | |
| 2016-09-07 13:46 | henry | Note Added: 0006842 | |
| 2016-09-07 13:53 | henry | Note Added: 0006843 | |
| 2016-09-07 14:29 | TomasR | Note Added: 0006844 | |
| 2016-09-07 14:37 | henry | Note Added: 0006845 | |
| 2016-09-07 15:00 | TomasR | Note Added: 0006846 | |
| 2016-09-07 15:21 | henry | Assigned To | => henry |
| 2016-09-07 15:21 | henry | Status | new => resolved |
| 2016-09-07 15:21 | henry | Resolution | open => fixed |
| 2016-09-07 15:21 | henry | Fixed in Version | => 4.x |
| 2016-09-07 15:21 | henry | Note Added: 0006847 |
