I am a new guys for mfix, i want to generent some particles with the size of 1e-7m in the inlet, then the particles to impact and adhere to a stable larger particle with the size of 3e-4m. But i cannot to let it running with some errors, just as followed:
The case can running if the particles in the inlet is about 5e-7m, but it be errors if reducing the particles to 1e-7m. It maybe attribute to the cells problem near the larger stable sphere particle. I am not sure.
The case is as followed, please help me to solve this problem and make it running. Thank you! try.10.4.zip (3.9 MB)
I am not sure this is doable. Your particles are way too small for DEM, the solids time step is 1E-11 second!! The error you see is because the des grid spacing is by default 3 times the particle diameter, and there is not enough memory to handle it. You could manually set the des grid size in the Solids>DEM pane, search grid partition to bypass this, but I doubt you can run such a simulation.
Thank you very much for your replay. but there still some questions.
why the particles size about 5e-7 m can be calculated, the 1e-7 is error? it is just closed.
I try to adjust the Solids>DEM pane search grid partition to 100, it can run at the particle size of 4e-7 m and the MESH - cell size of 1e-5 m. But there will be nothing remind if the particle size is 1e-7 m and the MESH - cell size is 1e-5 m, it is not running or no errors, just like the computer is stuck. If reducing the MESH - cell size to 2.5e-6 m, and the particle size is 1e-7 m or 5e-7, the error is reminded, as followed:
I am confused about that, in my opinion, the smaller the grid, the better it is for convergence. But in mfix, why it is no longer applicable.
3.how to calculate the solid time step at the particles size about 1e-7 m, as you mentioned above, it is about 1e-11 second. I want to know how to calculate.
Sorry to bother you.
There is a factor of 5 in the particle size which translates into a des grid cell count 125 (5x5x5) larger. You are likely running out of memory with the smaller particle.
The error you see is a meshing error, most probably because your cell size of 2.5 microns is below the meshing tolerances.
My suggestion is to go through the basic examples we provide through the GUI and gradually decrease the size of you domain/particle. You should also do a hand calculation of how many particles you plan to use. It is possible than DEM is not a modeling option for your type of application.
