[TharunSK]

I am trying to analyse the environmental effects on a machine tool through coupled flow-thermo structural simulations. The intended goal is to obtain HTC (heat transfer coefficients) values from CFX simulations and provide them as boundary data to transient thermal simulations. In reality, the stationary machine is subjected to air flow with velocity of 0.5m/s for around 300s. I need to create a simulation model which corresponds to this. My doubt are as follows:

1. Which CFX analysis should I perform to obtain HTCs (steady state or transient)?
2. I initially define HTCs from CFX as boundary convection data in transient thermal analysis. Initial temperature of the machine tool is also defined. Would it make sense to use the HTC value obtained (constant)from steady state for each time step in transient simulations? Or should I perform transient CFX simulation and provide the HTCs at each CFX time step to transient thermal time step?

Thanks!

[ghorrocks]

If you want the fluids and thermal/mechanical model to be closely coupled you should use the workbench coupling options. In this case it does not couple through HTC but more directly with heat fluxes.

This all depends on how complex and/or coupled the fluid and thermal fields are. If it is complex and/or coupled then you really should do it using Workbench coupling.

Your other questions:
Steady state or transient? That depends on what you are modelling. If you only care about the steady state performance then go SS, if you want transients you need a transient simulation. Pretty obvious really.

Definition of HTCs - as stated I am not convinced your approach is the best one. But you can mix steady state and transient in the coupled approach I suggest quite easily. You would only do this if the time scales of the different systems are significantly different (which is quite common).

[TharunSK]

Thanks Glenn!