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Old   January 14, 2010, 13:32
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sai ram
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hello everybody
i have a bunch of problems in fluent before stimulaion n after stimulation it follows as this way
1) i have four inlets for a micromixer n i am unable to know wat shud i keep in the "compute from" in "initialize" shud i select "all zones" or shud i select some inlet
2) i'm getting reverse flow when i stimulate the model, i dont no wats de reason can any one suggest me anything regarding this, i have tried outflow at output too.
3) i'm actual dealing with species mixing n mi aim is to know wheather the fluids are mixing in proper ratio or not, i hav no clue regading can any one help me thanx in advance
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Old   January 14, 2010, 20:27
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Initialize value is not important in steady simulation unless u got divergence.
compute from is also not important unless u got divergence.
As long as ur simulation converge, u are good.
I have no idea on the reverse flow, maybe its cause by the front inlet blocking it from flowing out.

species mixing can be check via species contour plot. The color of the contour can be mass fraction , molar fraction and more... check out on that one.
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Old   January 15, 2010, 11:49
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thanx herntan for ur reply
i think u r right because of front intel there is reverse flow, i will try to increase the velocity of back inlet so it may work
for species mixing the picture gives a nice idea n de way de fluids are mixing
wat i'm actually stuck here is wats de mass fraction of output of each fluid species, when u see this picture very little is at outflow which dnt make any sence, can u please help me in this if u hav any info..
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Old   January 16, 2010, 01:11
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your problem is of steady or unsteady state. if unsteady,what is the time step u have taken for simulation? i did face that problem i reduced my time step and it did work.
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Old   January 17, 2010, 21:14
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if u have 2 species of fluid mixed, its very hard to estimate their mass fraction.
I cannot understand what u mean by doesn't make sense.
Keep in mind that, mass fraction is the ratio of MASS for species 1 and species 2.
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Old   January 19, 2010, 12:04
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Quote:
Originally Posted by achy7pch View Post
your problem is of steady or unsteady state. if unsteady,what is the time step u have taken for simulation? i did face that problem i reduced my time step and it did work.
its a steady flow
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Old   January 19, 2010, 12:08
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Quote:
Originally Posted by herntan View Post
if u have 2 species of fluid mixed, its very hard to estimate their mass fraction.
I cannot understand what u mean by doesn't make sense.
Keep in mind that, mass fraction is the ratio of MASS for species 1 and species 2.
wat i'm willing to tell is if i sum all the mass fractions of each species it shud be 1. but in this case its not coming to one
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