INITIAL CONDITIONS in ANSYS CFX SOLVER

Mfaizan · January 20, 2015, 19:50

Hi all,

I am confused in understanding the term initial condition in CFX Solver. I have a back up file with 6000 iterations and I want to use this back up file as an initial condition for the next run. But I want to change the values of three coefficients in CFX-Pre. The three coefficients are Prandtl No, Ce1 and Ce2.

My fear is that the solver would may use the value of coefficients from initial condition back-up file.

Please suggest me about this- Would solver incorporate the new values of coefficients using initial condition back up file or not ??

Many thanks....

Lance · January 21, 2015, 01:22

I guess you could edit the .bak or .res file to be sure that your new values are in the initial values. Open up solver manager, tools/edit cfx solver file. Change the coefficients, then file/save. Now the new values should be present in your .bak/.res file and can be used as initial conditions.

Mfaizan · January 21, 2015, 01:58

Thanks Lance-

Please suggest this edit may or may not temper the statistical data of backup file which I intend to use as initial values.

Actually I am trying to reduce the overall computation time of Steady State analysis. I need first 5000 iterations at 10e-8 physical timescale to stabilize the solver and I would use this 5000 iteration data as initial values. I would then change the coefficient values and time step as well to analyze the effect.

Please suggest.

Kapi · January 22, 2015, 20:38

Hi Faizan,

You have to Edit your .def file, It will open Command file editor. You can change values in that and press "save" at the end.

No when you run your.def file, go to Tab "Initial Values" Select your 5000 Iteration result there. If you go down in that same page you will find something called "Continue History from" Make sure it is ticked. It will make sure you are using your history (5000 iteration result)

Now you can use your history with new values!

Hope it helps.
Cheers
KAPI

Mfaizan · January 22, 2015, 20:42

Thanks Kapi for your response- I appreciate

let me try this to see the effect of change of new values and reading of previous history.

I would post the outcome. I wish it works like you said.

Kapi · January 22, 2015, 20:44

It should work,

As soon as you run your .def file, it will start giving your initial values, you can check there if its same as your input.

January 20, 2015, 19:50	INITIAL CONDITIONS in ANSYS CFX SOLVER	#1
Mfaizan Member Faizan Join Date: Mar 2014 Posts: 76 Rep Power: 12	Hi all, I am confused in understanding the term initial condition in CFX Solver. I have a back up file with 6000 iterations and I want to use this back up file as an initial condition for the next run. But I want to change the values of three coefficients in CFX-Pre. The three coefficients are Prandtl No, Ce1 and Ce2. My fear is that the solver would may use the value of coefficients from initial condition back-up file. Please suggest me about this- Would solver incorporate the new values of coefficients using initial condition back up file or not ?? Many thanks....

January 21, 2015, 01:22		#2
Lance Senior Member Lance Join Date: Mar 2009 Posts: 669 Rep Power: 22	I guess you could edit the .bak or .res file to be sure that your new values are in the initial values. Open up solver manager, tools/edit cfx solver file. Change the coefficients, then file/save. Now the new values should be present in your .bak/.res file and can be used as initial conditions. Mfaizan likes this.

January 22, 2015, 20:38		#4
Kapi Senior Member Join Date: Apr 2014 Location: Melbourne Posts: 584 Rep Power: 14	Hi Faizan, You have to Edit your .def file, It will open Command file editor. You can change values in that and press "save" at the end. No when you run your.def file, go to Tab "Initial Values" Select your 5000 Iteration result there. If you go down in that same page you will find something called "Continue History from" Make sure it is ticked. It will make sure you are using your history (5000 iteration result) Now you can use your history with new values! Hope it helps. Cheers KAPI Mfaizan likes this.

January 22, 2015, 20:44		#6
Kapi Senior Member Join Date: Apr 2014 Location: Melbourne Posts: 584 Rep Power: 14	It should work, As soon as you run your .def file, it will start giving your initial values, you can check there if its same as your input. Mfaizan likes this.

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January 21, 2015, 01:58		#3
Mfaizan Member Faizan Join Date: Mar 2014 Posts: 76 Rep Power: 12	Thanks Lance- Please suggest this edit may or may not temper the statistical data of backup file which I intend to use as initial values. Actually I am trying to reduce the overall computation time of Steady State analysis. I need first 5000 iterations at 10e-8 physical timescale to stabilize the solver and I would use this 5000 iteration data as initial values. I would then change the coefficient values and time step as well to analyze the effect. Please suggest.

January 22, 2015, 20:42		#5
Mfaizan Member Faizan Join Date: Mar 2014 Posts: 76 Rep Power: 12	Thanks Kapi for your response- I appreciate let me try this to see the effect of change of new values and reading of previous history. I would post the outcome. I wish it works like you said.