

December 13, 2019 at 10:08 amblackbaddlSubscriber
Hi everyone,
I encountered a problem while postprocessing on HPC System. When switching from steadystate to transient solving I do not get the turbkinetic energy any more. I am not shure wether this is a technical issue or I did not get the concept completely yet.
I downloaded the last time step .dat file and tried it by hand. The same, no turb kinetic energy. What is the problem ?
These are my solver settings:
/define models solver pressure yes
/define operatingconditions gravity no
/define models energy yes no no no no
/define models viscous kwsst yes
/define models viscous curvaturecorrection yes
/define materials changecreate air , yes incompressibleidealgas , no yes sutherland , , , , no no no
;
;
;Solver Settings
;Pressure Velocity Coupling Scheme [20] ?
;; 20 for SIMPLE
;; 21 for SIMPLEC
;; 22 for PISO
;; 24 for Coupled
/solve set pvcoupling 21
;
;Convective discretization scheme for Pressure [10]
;; 10 for Standard
;; 14 for PRESTO!
;; 11 for Linear
;; 12 for Second Order
;; 13 for Body Force Weighted
/solve set discretizationscheme pressure 14
;
;Convective discretization scheme for Momentum [0]
;; 0 for First Order Upwind
;; 1 for Second Order Upwind
;; 2 for Power Law
;; 4 for QUICK
;; 6 for ThirdOrder MUSCL
/solve set discretizationscheme mom 6
;
;Convective discretization scheme for Energy [0]
;; 0 for First Order Upwind
;; 1 for Second Order Upwind
;; 2 for Power Law
;; 4 for QUICK
;; 6 for ThirdOrder MUSCL
/solve set discretizationscheme temperature 6
;
;Convective discretization scheme for Turbulence Kinetic Energy [0]
;; 0 for First Order Upwind
;; 1 for Second Order Upwind
;; 2 for Power Law
;; 4 for QUICK
;; 6 for ThirdOrder MUSCL
/solve set discretizationscheme k 6
;
;Convective discretization scheme for Turbulence Dissipation Rate [0]
;; 0 for First Order Upwind
;; 1 for Second Order Upwind
;; 2 for Power Law
;; 4 for QUICK
;; 6 for ThirdOrder MUSCL
/solve set discretizationscheme omega 6
;
;set underrelaxation factors when divergence occurs
/solve set underrelaxation temperature 0.6
/solve set underrelaxation turbviscosity 0.6
;/solve set underrelaxation omega 0.6
;/solve set underrelaxation pressure 0.6
;/solve set unerrelaxation mom 0.4
;/solve set underrelaxation density 0.8
;/solve set underrelaxation bodyforce 0.7
;
/solve set highordertermrelaxation enable? yes
;
/solve initialize computedefaults all
/solve initialize hybinitialization
;/solve iterate numberofiterate
/solve set timestep 0.01
/solve dualtimeiterate 150 300
;
By the way the solution converged by itself and the residuals of K and omega existed of course
Thank you in advance

December 13, 2019 at 4:32 pmDrAmineAnsys EmployeeAre u post processing in Fluent,? What is missing? You are able to solve TKE and you its residual.

December 14, 2019 at 4:58 pmblackbaddlSubscriber
Yes I do postprocessing in fluent. Basically everything affecting turbulance is missing in postprocessing. I was able to solve the case perfectly and because of the residuals I assumed that turbulance values should have been callculated.
The are the residuals of the last timestep I downloaded from the HPC to look into that by hand.
iter continuity xvelocity yvelocity zvelocity energy k omega time/iter
12759 1.2295e03 2.2280e06 1.6802e06 2.1652e06 9.5707e17 2.5318e05 4.3953e05 0:07:09 234
12760 1.1969e03 2.1917e06 1.6538e06 2.1311e06 9.5311e17 2.4826e05 4.3069e05 0:07:05 233
12761 1.1655e03 2.1563e06 1.6278e06 2.0977e06 9.5589e17 2.4347e05 4.2149e05 0:07:01 232
12762 1.1354e03 2.1216e06 1.6023e06 2.0649e06 9.5669e17 2.3879e05 4.1312e05 0:06:57 231
12763 1.1060e03 2.0877e06 1.5775e06 2.0329e06 9.5496e17 2.3423e05 4.0452e05 0:06:54 230
12764 1.0772e03 2.0543e06 1.5530e06 2.0013e06 9.5454e17 2.2977e05 3.9660e05 0:06:51 229
12765 1.0499e03 2.0216e06 1.5290e06 1.9703e06 9.5616e17 2.2542e05 3.8836e05 0:06:49 228
12766 1.0232e03 1.9897e06 1.5054e06 1.9400e06 9.5554e17 2.2117e05 3.8086e05 0:06:46 227
!12767 solution is converged
12767 9.9754e04 1.9584e06 1.4823e06 1.9103e06 9.5626e17 2.1703e05 3.7303e05 0:06:44 226
Flow time = 1.5s, time step = 150
So the goal is to do a basic postprocessing on HPC System because each of these time steps has 35 GB of data.

December 14, 2019 at 5:12 pm

December 16, 2019 at 6:12 amDrAmineAnsys EmployeeThat is weird can you start a dummy case just to check if you face same issue

January 20, 2020 at 1:18 pmblackbaddlSubscriber
Sorry for the very late reply,
the HPC system was down for quite a while due to maintance and I have not been at the project for some time because of being sick.
However, yes there is the same issue in a dummy case.... It is very weird. We decided to stay with steady state simulations because there is not a real added value in transient solutions for our project at this moment. But this might be worth looking into in more detail some time in the future.....
I faced another big big problem with Fluent on HPC. I am not able to mesh. This a lot worse for us at the moment as we are trying to implement an efficent workflow "backwards". (Just the order of implementation and development)
But I will post another question with details on it. Would be great if somebody is looking into that.
Thank you

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