topic Re: Need help applying initial temperature to moving solid in CFD Forum

Need help applying initial temperature to moving solid

Anonymous — Tue, 07 Mar 2017 13:01:17 GMT

Hello everybody,

I am having trouble applying Initial temperature to a moving solid. I set inital Temperatur to static 25°C to all parts (moving and non moving). When I start my simulation the non moving parts have a Temperatur as initialised of 25°C but the moving solid starts at 0°C.

So my question is, how do I set an inital temperature to a moving solid?
All help is appreciated.

Re: Need help applying initial temperature to moving solid

Jon.Wilde — Tue, 07 Mar 2017 14:28:31 GMT

Are you applying to volumes (not surfaces)? Fluid as well as solids?

What else is assigned within the model?

Are you starting with the part outside of the model initially and using 'initial position' to move it into place? This is recommended 🙂

Re: Need help applying initial temperature to moving solid

Anonymous — Tue, 07 Mar 2017 19:15:45 GMT

I am applying to volumes. The initial temperature I applied to all the non moving parts are working fine. The only moving part is going through a heating shaft. Objective of this simulation is to analyze the temperature profil of the moving part in the heating shaft. My issue is that the moving part is entering the heating shaft with a temperature of 0°C even though I have set an initial temperature of 25°C.

Thanks for your help Jon

Re: Need help applying initial temperature to moving solid

Jon.Wilde — Wed, 08 Mar 2017 08:57:49 GMT

Not sure, sounds a bit weird 🙂

Could you share a support file/CFZ?

Re: Need help applying initial temperature to moving solid

Anonymous — Wed, 08 Mar 2017 13:47:11 GMT

Here is a simplified version of my simulation:

Re: Need help applying initial temperature to moving solid

Jon.Wilde — Wed, 08 Mar 2017 14:51:02 GMT

Thanks - we need a CFZ though 😉

Re: Need help applying initial temperature to moving solid

Anonymous — Wed, 08 Mar 2017 15:24:58 GMT

🙂

Re: Need help applying initial temperature to moving solid

Jon.Wilde — Thu, 09 Mar 2017 08:30:34 GMT

Thanks 🙂

A few things:

Start with the moving part outside of the model and use 'initial position' to move it into place - this needs a CAD change
Enable 'Wall Layers' (boundary layer) before running - off by default with motion analyses and very useful to have on with heat transfer
The moving part and surrounding fluid really need the same mesh. I would use a manual mesh here with a refinement region and the solid with the same mesh size
You have 'auto forced convection' on. This runs flow first and thermal second and cannot be used in this type of analysis as you need both to be run together. Please turn it off 🙂
I would start without radiation, get it running smoothly and then enable (usually a quicker approach to speed up testing)
A 10s time step is really large considering what is happening, I would start smaller, maybe 1s or even less with something like 3 inner iterations
You can set time steps to run to -1 if you like and then set a fixed stop time - easier to calculate

That ought to solve it!

Thanks,

Jon

Re: Need help applying initial temperature to moving solid

Anonymous — Thu, 09 Mar 2017 13:11:55 GMT

Hey Jon,

thanks a lot for your help.

Best,
J