How to define a fixed velocity for a given mass flow rate on inlet

mqasimali · April 12, 2013, 03:13

hello,
I am simulating a turbulent flow through a vertical channel with some sort of blockage.
its mass flow rate at inlet is 0.3 kg/s
using mass flow rate = density* area* velocity for inlet i come up inlet velocity as 2.4 m/s
that is reasonable...
but when i step into fluent, i defined the mass flow rate exactly in vertical channel but inlet velocity is jumped up to 80m/s
how to fix this inlet velocity???
i am only defining the mass flow rate, rest i initialize the value from inlet that takes velocity in 80s, even if i keep it down but fianl form after iteration makes it deviate again.
in other words i want fixed velocity at inlet. help me out.
thankyou

ghost82 · April 12, 2013, 03:17

I think your solution is not converged, that's why your velocity field and other variables are wrong.

Daniele

mqasimali · April 12, 2013, 18:24

i tried different grids to check their independence, all yielded results in same pattern and it stops the results with comment solution is converged

April 12, 2013, 03:13	How to define a fixed velocity for a given mass flow rate on inlet	#1
mqasimali New Member Qasim Ali Join Date: Mar 2013 Location: Islamabad, Pakistan Posts: 18 Rep Power: 13	hello, I am simulating a turbulent flow through a vertical channel with some sort of blockage. its mass flow rate at inlet is 0.3 kg/s using mass flow rate = density* area* velocity for inlet i come up inlet velocity as 2.4 m/s that is reasonable... but when i step into fluent, i defined the mass flow rate exactly in vertical channel but inlet velocity is jumped up to 80m/s how to fix this inlet velocity??? i am only defining the mass flow rate, rest i initialize the value from inlet that takes velocity in 80s, even if i keep it down but fianl form after iteration makes it deviate again. in other words i want fixed velocity at inlet. help me out. thankyou

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April 12, 2013, 03:17		#2
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 27	I think your solution is not converged, that's why your velocity field and other variables are wrong. Daniele

April 12, 2013, 18:24		#3
mqasimali New Member Qasim Ali Join Date: Mar 2013 Location: Islamabad, Pakistan Posts: 18 Rep Power: 13	i tried different grids to check their independence, all yielded results in same pattern and it stops the results with comment solution is converged