[Chris_321]

I want to do a basic rocket start simulation. To get started soon, my first simulation is gonna run "cold" without the propulution engine. Im Not interessted into ground effects so the simulation will start way above ground. The issues im facing are the following:

1. How is it possible in CFX to change the density, and viscosity timedependent ?(for the rising rocket )

2. How can i simulate the heat up of the cone nose? Do i have to set the Temp = Temp + DeltaT( fnct of capacivity and Heat) or can i set a specific boundary ? I couldnt remember that the Wall boundary is heating up or am i wrong?

[ghorrocks]

Q1: Density and viscosity of what? You can make these parameters functions of many things. Is it the air passing the rocket?

Q2: You could do this as a Conjugate Heat Transfer simulation and model the heating of the cone nose but I would recommend agains this. The separation of time scales between fluid and thermal time scales will mean this simulation is not manageable. I suspect you will find a far better way of doing it is to model it as a series of steady state simulations with the cone at various temperatures as it heats up. Then you can get the heat flux to the cone versus temperature and use a simple numerical simulation to get the heat up characteristic.

[Chris_321]

You are right! i Do steady simulations and make it in steps. As always Thank you