Particle velocity in solid-gas flow
I am running a 2D simulation for FCC riser in ANSYS Fluent 14 using Eulerian multiphase model for the solid-gas flow. I use the standard k-epsolon per phase turbulence model with the standard wall function. The geometry is so simple axisymmetric pipe. The inlet boundary conditions for both phases were coded in UDF .c file and interpreted in the fluent setting up.
When running the case, it converged after 100's of iterations but the outflow particle velocity profile is not parabolic (not fully developed). It decreases slowly from the centre then fall sharply near the wall. Some times has another peak (maxima) near the wall as if it is an annular core flow.
I used no slip conditions for both phases at the wall, also tried different specularity coefficients for the solid phase, but I got same results.
When plotting the wall Y+ value for the solid phase, it changed sharply from 25 to 300 at the inlet then remain between 150 and 160 for the rest of the meters along the wall. And for the gas phase it stays below 20.
I don't know what to do to get the parabolic profile at the out let?
I appreciate any kind of help,
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