Should coupled solver be used when flow is either greater or atleast equal to 1.5 Mach #. And if flow is below 1 Mach #, seggregated solver should be preferred. I need some experienced person to advise. I do know what fluent manuals say.(Use coupled solver for compressible flow, while compressible flow regime starts right from 0.3 Mach.)

With Regards

Ejaz Ahmed

i have used it with 0.17 mach and it works fine.

Zxaar

dear, thanx for ur couteous responce. But make one thing calrified. You used it, and its works fine for 0.17 Mach#. ("it" either stands for seggregated or coupled solver)

Plz make it clear.

With Regards

Ejaz Ahmed

ohh i din't make my self clear, i assume that you have doubts about using coupled solver for low mach, so i said i used it (coupled solver) at 0.17 and and it works fine.

Thanx for sharing your experience. But what do u advice for 0.7 Mach flow. Dear do you got some knowlege of solving heat transfer problem in concentric pipe heat exchanger. where pipe flow consists of gas at 0.7 mach and in annulus we got gas at 50m/s. Length of exchanger is 1 m. Now i am achieving the mass conservation but not the energy conservation.

With Regards

Ejaz Ahmed