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niraj May 9, 2006 06:01

bubble columnn dynamics
i m new use for gambit n fluent.i m doing a project on bubble column(radius 0.07m height=1.30m).for this i formed a 2d axis-symmetric euler simulation.for this i formed a grid by follwing: radius :10 cells *3.5mm,20 cells * 1.75mm height : 40 cells *5.0mm,110 cells *10mm

for this i fored a vertex (real) on (0,0,0),(0.035,0,0)(0.07,0,0),(0,0.2,0)),(0.07,0.2 ,0),(0,1.3,0),(0.035,1.3,0),(0.07,1.3,0)

by joing all vertex fomred eddges expect on middle(0.035) formed virtual edges[i.e.1)vitual edge by joing real vertex (0.035,1.3,0) and(0.035,0,0) 2nd vitual edge by joing (0,0.2,0) and (0.07,0.2,0)]

so question is can i formed vitual ege by joing real vertex ?

again boundry condition : lower edge as velocity inlet upper edge as vent left edge as a axis right axis as a wall

now question is upper edge is pressure outlet or as only vent? and also i have a confusion on velocity inlet as gas sparger sparge the gas only by central nozzle with 0.3 mm orifice inlet( weather in this problem i set boundry condition to lower edge as a velocity inlet)

by exporting this edge to fluent now i m geting a error as "non-positive face area exist" and Grid check failed

please help me to fing out solution i will greatful to u

niraj mtech chemical

mike May 9, 2006 11:51

Re: bubble columnn dynamics
dear niraj...

Oulet conditions can be either Pressure outltet or outflow conditins. When u r using turbulence models... then u need to denfine the value of k and epsiln at both inlet and oulet. By selecting u need to define these values at oulet. however u can use outflow conditions provided ur outlet is quite far from the real flow analysis domain. then u dont need to specify these values at the outlet..

hope it helps.

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