Discussion Forum

I am trying to set up a simple test problem. A solid sphere falling through water, accelerating until it reaches terminal velocity. I am a fairly new user so I apologise in advance if I missed something obvious

My plan was to calculate the accelaration by subtracting the drag force on the sphere at the previous time step from the gravitational acceleration. Use the accelaration and the time step length to increment inlet flow velocity. repeat until acceleration equals zero.

I have set up the flow around the sphere no problem. I can calulate the drag force no problem. I am just a bit stuck on how to get the previous time step drag force.

I calculate drag by integrating spf.T_stressy over the sphere surface. I have been trying to figure out how to use the prev command. I have added the domain ODE to my component. I am just stuck on what to set the ODE to and then how to use the result of the ODE to calculate last time step drag. Any guidance would be welcomed.

Is there an easier way to calculate this? Am I taking the correct approach?

Thanks in advance for your assistance.