turbulent viscusity ratio

reza

dear friends hi i am new to fluent and i am studying air flow in the air intake system for gas turbine. the above system is itended to filter the air and my simulation runs on fluent 5.2.3 and air speed is around 50 m/s and the inlet boundary condition for air is atmospheric pressure at the inlet openings. my question is why i have the backflow situation while trying to run the case and also i have increasing trubulence viscusity ratio reported to increase as iteration gets ahead.

i use a satdard k-e modle and also i have a velocity inlet bc with -30 m/s at the compressors inlet section of the whole domain (i mean the outlet is the opening where the gas turbine's compressor inlet is located.

thanks in advance reza