Learning Forum

[despinosam]

Hello,

I am trying to simulate a fluidized bed in 3D. I have nitrogen as primary phase and glass beads as secondary phase. I have been running my simulation with 1e-3 time step size and 1.5e-4 time step size, both with 40 iterations. However, in both cases when the simulation gets to 6580 iterations I get a floating point exception as shown in the picture. I do not know how to solve this problem, I have tried re doing the simulation but keep getting the same error at the same number of iteration. To get convergence I tried what the user guide suggests that is shutting down volume fraction equation for the first time steps. I have also attatched my geometry.

I would truly appreciate any kind of help.

[Rob]

Check the mesh, and also think about switching to the transient solver after a shorter period of steady state flow.   If you do the sums, have you reached the minimum fluidisation velocity, or are you heading into a bubbly bed regime? 

[despinosam]

How many iterations in steady state should I run? I've tried with 1000 but velocity residual doesn't go lower than 1e-1, also after that I run the transient case and keep getting peaks on my solution. 

I've been using the velocity to achieve bubbly regime but after reading your message I changed it to minimun fluidization velocity. 

[Rob]

You need to decide why you're running the model.  Multiphase tends to be transient, so may fail steady or fail to converge depending on how transient it actually is. 

[despinosam]

I need to run it in bubbly regime. 

[despinosam]

Should I run the steady state with or without the Volume Fraction Equation?