On the issue of two-dimensional simulation

MFiX How to
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#1

Hello, researcher. I have two very confusing questions, as follows:

  1. I am currently confused about the concept of two-dimensional simulation, as shown in the following figure. Regardless of the size of the rectangular model, as long as the number of grids in the Z-axis direction is 1, it can be considered a two-dimensional simulation. Is this understanding correct?

  2. Do we need to establish wall boundaries when conducting two-dimensional simulations? I checked the user manual and said: as long as the number of grids in the Z-axis direction is 1, there is no need to establish wall boundaries. If that’s the case, what should I do when I need to set the boundary temperature for 2D simulation?

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#2

Can someone help me? Thank you very much.

#3

Hi. Most of the MFiX team is on holiday break. We will get back to you as soon as possible.

#4

I believe you are correct about question #1 - a simulation with a single cell in the Z-direction is considered 2-dimensional, regardless of the size in the Z axis.

Regarding question #2 - although it is not necessary to set up the Z-boundary walls, I believe that it is still permissible to do so, for example if you need to specify wall temperature, etc.

#5

Hello Charles, I’d like to ask you how the wall thermal conductivity mfix is calculated when the z-boundary wall is not defined.

#6

It would be adiabatic wall by default.

#7

Thanks Jeff, but why is there still a very small particle-fluid-wall heat conduction source term for particles at the front and rear walls.

#8

Can you please show us what you mean?

#9

Sorry Jeff it was me who wasn’t clear. I was asking, I found that when in pseudo-2D, if the front and back wall surfaces are not defined, conductive heat transfer between the front and back wall surfaces and the particles still occurs for particles near the front and back wall surfaces.