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 harry March 11, 2009 02:57

mixing quality simulation

Hello All,

I'm involved in a simulation addressing the mixing quality between two kinds of liquids in a micromixer. Dimensionless parameter &alpha; was defined with the maximum standard deviation to describe the mixing quality between species along a cross section:&alpha;=1âˆ' sqrt(&sigma;2M/&sigma;2max), where &sigma;2max is the maximum variance of the species and &sigma;2M is the mean square deviation of concentration field: and cM is the mean concentration distribution of the species i over n elements of the mesh in a certain cross section of the mixing channel,

my question is how to achieve this using CFX? Thanks for your help.

 harry March 11, 2009 11:49

Re: mixing quality simulation

Dear all,

is there anyone who could help me? Take T-shape mixer as an example, two different fluids come inside the mixer from two inlets , flow along a mixing channel after junction and get out from one common outlet,I need to figure out the mixing efficiency in the correspondently different cross section of the mixing channel, and this mixing efficiency is based on the concentration distribution on that cross section.

This requires to calculate average concentration of that cross section , but to do this, you need to know the specific concentration value of some sampling points on this section, my question is how I can define these points and their concentration? And how should I setup these parameters in CFX? Do I need to create a new variable called concentration in the software?

Thanks a lot.

 Glenn Horrocks March 11, 2009 22:26

Re: mixing quality simulation

Hi,

You should be able to do this in CEL, using the volumeInt() and areaInt() functions.

Regards, Glenn

 harry March 12, 2009 04:34

Re: mixing quality simulation

Hello Glenn,

Thank you very much for your prompt reply. I noticed we can also use Danckwerts' intensity of segregation(Danckwerts, 1952) to define the mixing efficiency,

IS =&sigma;^2/&sigma;max^2,with &sigma;^2 =volumeInt[(C-¯c)^2]/|V|

where where ¯c denotes the mean value of the concentration field c and &sigma;max^2 is a reference value.

You did grant me a direction to approach this, sine I'm a new comer to touch with CFX, could you please specify it in detailed, like, how to express the above definition with CEL expression?

Best Wishes

Harry

 Glenn Horrocks March 12, 2009 17:24

Re: mixing quality simulation

Hi,

Sorry, don't have time to work it all out for you. Just work through it one step at a time and you will get there.

¯c might come from something like volumeAve(Variable Name)@Location. Look in the CEL Expression guide in the Reference manual for details of variable names.

Glenn Horrocks

 sairam May 8, 2010 14:36

intensity of mixing

Quote:
 Originally Posted by harry ;92314 Hello Glenn, Thank you very much for your prompt reply. I noticed we can also use Danckwerts' intensity of segregation(Danckwerts, 1952) to define the mixing efficiency, IS =σ^2/σmax^2,with σ^2 =volumeInt[(C-¯c)^2]/|V| where where ¯c denotes the mean value of the concentration field c and σmax^2 is a reference value. You did grant me a direction to approach this, sine I'm a new comer to touch with CFX, could you please specify it in detailed, like, how to express the above definition with CEL expression? Thanks for your help in advance. Best Wishes Harry
hii harry

i have the same problem like u. can you help me in finding the intensity of mixing please it would be really helpfull dude

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