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-   -   Initial values (http://www.cfd-online.com/Forums/cfx/74138-initial-values.html)

seojaho March 25, 2010 09:52

Initial values
 
Hi,

I have a problem that when I run the CFX-solver.

I have two domains in my cfx model, which are a mould (steel) and hot polymer, respectively.Through 1st simulation run (this represents 1st cycle of injection moulding process) where hot polymer's temperature, 204C is given only initially (i..e, initial condition for the hot polymer domain),
we can get some temperature distribution of the "mould domain" at the end of 1st simulation.

Then, I want to use this temperature distribution of the mould obtained from the 1st simulation run as initial temperature of the mould for 2nd simulation run ( 2nd cycle of injection moulding process) while old polymer (in the 1st cycle) is replaced by the new one with the same temp., 204C initially used for 1st simulation run (1st cycle) and thus the same initial condition for the "hot polymer domain" should be given for the 2nd simulation run.

In brief, I just want to use the previous result file to provide initial values (temp.) of ONLY "the mould domain" for the next simulation, because the polymer's initial condition should be the same for every cycle (every run)."

When I used the 1st run's result file (res) for the 2nd simulation with the option of 'Interpolate initial values onto Def file mesh', the 2nd simulation properly uses the temp. of "the mould domain" obtained from 1st simulation result file as initial value, but the initial condition (204C) of the "hot polymer" for the 2nd simulation which is the same one for the 1st cycle is not maintained. (i.e., the initial condition of the hot polymer is ignored in the 2nd simulation run).

Please let me know how to solve this problem.
Thank you so much.

Jaho

ghorrocks March 25, 2010 17:39

Look at CFX-Pre, and check out automatic, automatic with value and value options. This allows you to set what variables are read in from initial guesses and which are directly specified.

seojaho March 26, 2010 23:51

Dear Glenn Horrocks,

Thank you so much for your kind reply.
According to your advice, I changed the option of initial conditions under initialisation of only "mould domain" from automatic with value to automatic while the option of initial conditions of hot polymer domain is chosen with 'automatic with value (204C) because the hot polymer's temperature should be reset as 204C in the begining of each simulation run.

However, regardless of this, the next simulation still uses the temperature of mould obtained from the previous simulation as initial temp. for next simulation succesfully but the initial temp. (intitial condition, 204C) of the polymer is ignored (in other words, 204C as initial condition is not applied for the next simulation and instead the temp. of polymer from the previous simulation is is used for the next simulation consecutively).
(There is no difference between the cfx for the previous simulation and one for the next simulation)
If you have any good advice, please let me know about it.
If you want, I can send my cfx file... Thanks again and have a great day.

Sincerely,
Jaho

ghorrocks March 27, 2010 06:42

The automatic with value option uses the nominated value if no initial condition exists, but uses the initial condition if it exists. This is not what you want for temperature. You want the simple value option. This sets it to the nominated value, regardless of whether an initial condition is set.

seojaho April 4, 2010 17:44

Dear Glenn Horrocks,

I am sorry for late replying.
Thank you so much for your help. It's really helpful.
Have a great day~!

Jaho

Ridley August 10, 2010 06:28

Hi, I have a similar problem, as I want to initialize a solid domain with the final values from a previous run, but the fluid domain should have the values specified in CFX-Pre (transient simulation). Is it right that this is not possible with CFX 12.1 as there are only the options `automatic´ and `automatic with value´ which means that the domain is always initialized with the specified initial values file if there is one or is there another way to do this? Thanks for help!

ghorrocks August 10, 2010 07:27

You can set initial conditions by domain so one domain can be a defined value and another can be loaded from an initial condition file.

Ridley August 10, 2010 08:53

Hi, thanks for your reply. You´re right but the problem is that the solver uses the values from the specified initial values file which I need to initialize the solid domain. As a consequence the initial values for the fluid domain which I specify in CFX-Pre are ignored.


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