I'm attempting to carry out a flow simulation to look at the temperatures within a solid; for purposes of simplicity I have created a cube to test on. The boundary conditions necessary are:

The simulation uses air and titanium as the fluid and solid properties.

On applying these boundary conditions using "Total pressure" and "Static pressure" for the inlet and outlet flows respectively, the following cut plot is attained:

Which looks OK until you realise that the minimum temperature, 955 K, is below any of the input conditions (min. 986 K at flow inlet).

From the moment of entry in fact, the flow looses heat (which does not make sense as it has a lower temperature than the rest of the block), see below: NB different temp. scale

If anyone has any ideas on what is going on, and why this is an unsuccessful simulation, that would be greatly appreciated.

Additional comment: For the outlet I would like to set simply a pressure outlet without having to define end temperature which it asks for under thermodynamic properties - I think it is over-constrained as is...?

Thanks, Euan

Hi Chris, thanks for explaining the temperature setting on the static pressure, that makes sense to me now.

The initial temp was 273 K and I changed it to 1200 K to see if this would help but it has no impact on the outcome, which makes sense as it's an initial temperature and will converge to the boundary conditions. This is in a fluid domain yes. All goals were used for convergence, but as I understand there is no necessity for defined goals in the first place. I must admit that I am not entirely sure that I understand what 'convergence' is used for though.

I have continued working on the simulation and seeked help from a colleague that noticed that the mach number may have had a role to play. Using some theory in the form of the steady flow energy equation (SFEE) it can be shown that:

T0 / T = 1 + ((gamma-1)/2)*Mach^2

This equation shows how the temperature can in fact drop at higher Mach numbers. This has explained the odd plots.

Thanks for your help and suggestions Chris