Buoyancy Driven Flow - HELP!
 

Hello,

I have been modeling steady state vehicle aerodynamics for a few years now and I am faced with a simple problem yet I can't seem to get a solution, can anybody help me?

I have a land rover and a livestock trailer. In most of my simulations of turbulent flow, air flows through a duct surrounding the vehicles and that is simple enough. However, I want to look at a flow speed of zero.

There are CAD models of animals which I have inside the livestock trailer and they produce heat. I just want to model the temperature gradients inside the trailer. I have followed the help in Fluent and changed the boundary conditions of the duct I used for airflow calculations. So now, all the external boundaries are pressure outlets at asmospheric pressure and the vehicles and animals are walls. However, the solution always diverges.

What am I doing wrong!?! Can anybody give me a simple overview of the steps required to model this type of flow? Thank you for your time. Best regards,

Carlos.

Re: Buoyancy Driven Flow - HELP!
 

Use body force weighted for pressure, gravity enabled, ideal gas and ensure boundaries are far enough away from heat source

Re: Buoyancy Driven Flow - HELP!
 

Are you specifying isothermal wall as BC for the livestocks or u treat them as conjugate heat transfering sources with volumetric heat generation. I agree with red melon you need to specify the gravity as -9.81m/s2, and enable ideal gas assumption. Its not a must to have the boundary quite far away as u r specifying pressure BC.