[marsa27]

Hi, I would like to know if it possible in CFX to export the temperature field of some domains from a solution, to import them as an initial condition of a subsequent simulation only in the domains concerned.
Thanks.
Davide

[ghorrocks]

Yes, you can define initial conditions per domain. If you set the initial condition to "Automatic with value" it uses an initial condition value if it exists, otherwise it uses the defined value. If you set the initial condition to "Value" it uses the value you define. Do this in each domain and you can set where the initial condition comes from.

[marsa27]

Originally Posted by ghorrocks

Yes, you can define initial conditions per domain. If you set the initial condition to "Automatic with value" it uses an initial condition value if it exists, otherwise it uses the defined value. If you set the initial condition to "Value" it uses the value you define. Do this in each domain and you can set where the initial condition comes from.

But is it not necessary to extrapolate a file to be interpolated in a similar way to Fluent? I ask because I would like to set as the initial condition the exact temperature profile to be applied to a cast iron mold (solid domain) for forming a glass bottle. Instead I wouldn't want to initialize any temperature or even any VOF field for the glass in the fluid domain

[ghorrocks]

I have no idea what extrapolation in Fluent involves, and cannot see why it is relevant to CFX. You set initial conditions in CFX as I described (along with a whole bunch of other options).

[marsa27]

Originally Posted by ghorrocks

I have no idea what extrapolation in Fluent involves, and cannot see why it is relevant to CFX. You set initial conditions in CFX as I described (along with a whole bunch of other options).

but the initialization allows to set a uniform temperature throughout the domain, I would like to know how to initialize a temperature field that varies in each coordinate, according the solution of a previous simulation

[Opaque]

Originally Posted by marsa27

but the initialization allows to set a uniform temperature throughout the domain, I would like to know how to initialize a temperature field that varies in each coordinate, according to the solution of a previous simulation

Not sure where you are getting such information, in ANSYS CFX nearly every widget that takes a floating value, takes an expression as well; therefore, the initial value is NOT restricted to a uniform value.

Regardless of where the initial value comes from, if you explain how you plan to work with the different setups will help others to advise on the best solution.

[AtoHM]

In CFX you can use a result file and its temperature filed to start the new simulation with. This can be done by either interpolation, initialisation or, if you just want the temperature field and nothing else, you can export it as a csv file in Post (should be under File->Export to text or something like this). Maybe this can be used for Fluent as well, I am not sure.

[marsa27]

I have to simulate the forming of a glass bottle by doing a VOF calculation with coupled heat exchange thanks to the presence also of the solid domain. When the glass enters the fluid domain in the mold, I would like the solid domain to not lose the thermal history of the formation cycle of the previous bottle. For this reason I would like to know how to initialize only the temperature field in the solid domain for a new simulation

[ghorrocks]

The method I described in my first post will do this. If you want to take the initial condition and just take a bit off it (maybe to model heat lost between cycles) then use a source term which acts on the first time step to remove the amount of heat you want to loose between cycles.

[marsa27]

Originally Posted by ghorrocks

The method I described in my first post will do this. If you want to take the initial condition and just take a bit off it (maybe to model heat lost between cycles) then use a source term which acts on the first time step to remove the amount of heat you want to loose between cycles.

yes but with the initialization of each domain it is not possible to set a 3D distribution for the temperature field or am I wrong? I have always known that a uniform value or a function can be set but not a three-dimensional field

[ghorrocks]

You can set it to a constant value, a CEL expression, an interpolation function or a user fortran function. Everything except the constant value can be a function of anything you like, including location.

For instance "step(x)" will return 0 where x<0, +1 where x>0 and 0.5 at exactly x=0. This is an example CEL function which returns a 3D distribution.

[marsa27]

Originally Posted by ghorrocks

You can set it to a constant value, a CEL expression, an interpolation function or a user fortran function. Everything except the constant value can be a function of anything you like, including location.

For instance "step(x)" will return 0 where x<0, +1 where x>0 and 0.5 at exactly x=0. This is an example CEL function which returns a 3D distribution.

I have to simulate a glass forming bottle, with a VOF model with also the solid domains for the mold.. I'm interested to use a previous simulation to initialize the temperature profile only in the solid domain, while the fluid domain (with the VOF model: air+glass) have to simulate witout any initialising.
How it possible to do it?

[ghorrocks]

As i described right back in the start in post #2. You can define different initial conditions in different domains. Set the cavity domain (containing the glass, air and VOF model) to have initial conditions of whatever your initial glass state is; and set the outer casing solid domain to have option "automatic with value" and give it an results file for the initial condition.

[marsa27]

Originally Posted by ghorrocks

As i described right back in the start in post #2. You can define different initial conditions in different domains. Set the cavity domain (containing the glass, air and VOF model) to have initial conditions of whatever your initial glass state is; and set the outer casing solid domain to have option "automatic with value" and give it an results file for the initial condition.

Excuse me, maybe I cannot to understand, but if in the solver I inilitialize the simulation with a .res file containing all the domain (both solids, both fluid) how it is possible specify to take from the initialization file only the temperature field of the solid domains (not of the fluid) and not the other variables? As I have tried and the simulation starts by taking also the temperature field of the fluid part (VOF) and also all the other variables (velocity, pressure, VOF, etc.). Instead I interested only at the temperature field of the solid to inilitialize a following simulation.

I tried to export a BC profile from the CFD Post of solid domains, but I can't get the user function I imported into CFX Pre into the initialization tab of the individual domains. Is there any technique of this type? Since in reality the BC profile to be exported is indicated for the boundary conditions (superficial) and not for the initial conditions in the volumes