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#21 |
New Member
Join Date: Aug 2016
Posts: 3
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This error is caused when the solver tries to find T from h (or another energy variable). The task is to find T from known h when h = cp(T) * T and this is solved by a simple Newton-approach.
T is estimated and then re-calculated until convergence is reached. Bad estimates can lead to negative temperatures and cause the error. It's not always easy to find out why the estimated T is bad, but some possible reasons have been mentioned previously: - bad mesh - bad interpolation schemes - bad thermophysical properties |
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#22 |
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Rebel Young
Join Date: Jul 2020
Posts: 2
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It occurred in rhoC and rhoP solvers.
The temperature limiter in fvOption does not work, because I add the minMax functions in controlDict. The minimum temperature in the fields is not negative. In my case , the error happened after about 30-100 time steps. So the negative initial temperature is in the sub-iteration. I can not find a solution so far... |
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#23 | |
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Rebel Young
Join Date: Jul 2020
Posts: 2
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Quote:
As your advice, in rhoCentralFoam solver, it solves rho and rhoE for estimating the temperature, which has the equation "e=cv*T" . For the normalized gas , the Cv is constant. So the negative initial temperature means the energy is negative? |
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#24 |
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Niko_choko
Join Date: Sep 2020
Location: Jupiter
Posts: 2
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Can confirm that changing mesh did work for me too.
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#25 |
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Jonathan Wells
Join Date: Oct 2020
Location: Indiana
Posts: 44
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I am having the same issue, but I don't have a mesh problem. My entire domain is uniform spacing in a rectangular grid, so there is no change in mesh size, aspect ratio, or skewness. The solution runs fine with coarser grids, but my current grid is in no way over-refined, as edge length is 1 mm. I am doing LES in rhoPimpleFoam.
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#26 |
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Jonathan Wells
Join Date: Oct 2020
Location: Indiana
Posts: 44
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As a follow-up, I noticed that for my grid the max Courant number was approaching 1 when I would get the error. I reduced the dt and solved my issue.
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#27 |
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Bineet Mehra
Join Date: Aug 2013
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#28 |
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saidc
Join Date: Feb 2020
Location: nowhere
Posts: 63
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Hi,
I'm having same problem in LES, I tried with refined mesh but the result is the same again. Also when i added temperature limit in fvOption it stops iterrate after like 200 iterates. Maybe the problem is in my boundary conditions. I'm open any suggestion. Files attached. Kind regards Said. checkMesh Code:
Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 34125 faces: 386106 internal faces: 380986 cells: 191773 faces per cell: 4 boundary patches: 3 point zones: 0 face zones: 0 cell zones: 2 Overall number of cells of each type: hexahedra: 0 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 191773 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology inlet 214 128 ok (non-closed singly connected) outlet 242 142 ok (non-closed singly connected) wall 4664 2372 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (-0.025 -0.125 -0.025) (0.025 0.125 0.025) Mesh has 3 geometric (non-empty/wedge) directions (1 1 1) Mesh has 3 solution (non-empty) directions (1 1 1) Boundary openness (8.44415e-17 -7.50933e-17 5.0822e-18) OK. Max cell openness = 2.41502e-16 OK. Max aspect ratio = 5.2589 OK. Minimum face area = 1.47893e-07. Maximum face area = 3.61292e-05. Face area magnitudes OK. Min volume = 2.65313e-11. Max volume = 6.60658e-08. Total volume = 0.000625. Cell volumes OK. Mesh non-orthogonality Max: 53.9367 average: 14.5269 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.518146 OK. Coupled point location match (average 0) OK. Mesh OK. End |
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#29 |
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Joao Coelho
Join Date: Jun 2021
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#30 |
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ZhuangLi
Join Date: Jan 2022
Posts: 13
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Hi Tobias,
I got into trouble with the negative temperature, could you give me some advice to deal with it? Thanks in advance! _______ Kind regards! Zhuangli |
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#31 | |
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Mahdi
Join Date: Jul 2012
Posts: 53
Rep Power: 14 ![]() |
Quote:
fvOptions limitTemperature crashing in compressibleInterFoam |
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#32 | |
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ZhuangLi
Join Date: Jan 2022
Posts: 13
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Quote:
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#33 |
Member
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I ran buoyantSimpleFoam with Boussinesq as the EoS but it crashed at Time=3 for ‘negative initial temperature T0=-24’ error. fvOptions limitT solves it, but the resulting flow pattern is unphysical. I would like to trace back in the code to find out what causes T0 < 0 (T0 is given as a fixed number in the EquationOfState subdict in constant/thermophysicalProperties as one of the requisite parameters for the Boussinesq EoS.)
My question: How to trace back from the thermol.H at line 300 (grep -r 'Negative initial temperature T0' reports it as the only place where this text appears under src/) through the source codes? thermol.H is at https://cpp.openfoam.org/v9/thermoI_8H_source.html td p { orphans: 0; widows: 0; background: transparent }p { line-height: 115%; margin-bottom: 0.1in; background: transparent } |
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#34 | |
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Erdem
Join Date: May 2022
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Quote:
Thanks for your help. |
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Tags |
chtmultiregionsimpefoam, temperature calculation |
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