[Muneeb]

Respected Sir

I am working on simulation of non premixed combustion of a gas turbine engine afterburner in FLUENT. when I run the simulation for ADIABATIC CASE in non premixed combustion (energy eqn 'OFF' , compressibility effects disabled) the solution is easily converged and reasonable results are obtained. When I enable the compressibility effects in non premixed combustion window followed by recalculating the pdf table, the solution does not proceed beyond 05 iterations with error 'Divergence in AMG solver: pressure correction'

I tried to run the solution with species model OFF (combustion OFF), taking Air as ideal gas (compressible + energy Eqn ON), solution is converged and reasonable results are achieved. Problem is encountered only with enabling the compressibility effects while modeling non premixed combustion.

Further details are as follow:
Mesh size: 6 Million elements (hexahedral + tetrahedral)
steady state
standard k-epsilon turbulence model
radiation: OFF
periodic boundary conditions (axisymmetric 30 deg sector) with mass flow air and fuel inlets and pressure outlet
solver: Coupled (Courant number 0.3)

You are kindly requested to please advice how to proceed with compressibility effects enabled in modeling non premixed combustion.

Thanks