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-   -   simulating coanda effect (http://www.cfd-online.com/Forums/fluent/43235-simulating-coanda-effect.html)

alfin January 3, 2007 16:52

simulating coanda effect
 
hi

i would like to know whether anybody has simulated coanda effect using fluent.


Rajesh January 4, 2007 01:59

Re: simulating coanda effect
 
I did.....

alfin January 4, 2007 12:04

Re: simulating coanda effect
 
hi

i would like to know wht turbulence model you used. could you please help me ouyt with that

ALFIN

Rajesh January 4, 2007 22:06

Re: simulating coanda effect
 
Dear Alfin,

I tried to simulate the flow field in a Coanda ejector where a primary jet flowing over a Coanda surafce drags the secondary flow into the ejector. I wanted to calcualte the sceondary mass flow rate and the length at which both the flows are completely mixed. I used standard k-E model and got reasonable results.. What's the problem you are trying? and what exactly do you what to know?

regards, rajesh


alfin January 5, 2007 12:20

Re: simulating coanda effect
 
hi rajesh

i want to simulate the following

There is a foil (say a very thin strip of aluminium in the form of a cantilever beam)

there is a hindrance above the foil at a reasonable diatance when i blow the air above the hindrance the air removes the air between the hindrance and the foil due to coanda effect

this makes the foil bend upwards due to pressure difference above and below the foil

i just wanted to know the pressure plot between the hindrance and the foil

i hope i made myself clear


Rajesh January 5, 2007 22:21

Re: simulating coanda effect
 
I think you can do this problem in fluent quite easily. You can use segregated/coupled solver depending on the Mach number of the airflow (I presume that the Mach number is very low..if its lower that 0.3, then you can use the segregated solver) Use pressure inlet for the incoming air and pressure outlet for all other boundaries with atmospheric pressure values (...again depending on your air speed). If you have high air speeds, you can impose atmospheric boundary conditons by extendng your domain.. You can define a line in between the hindrance and the airfoil and plot the static pressure there. Standard K-E (wall functions) is suffient for getting reasonable results. Try with small no of grids first(..may be 5000 or 6000). That will give you an idea how the solution progresses. Then try increasing the grids till the static pressure plot doesn't change with number of grids.

hope this helps..

all the best Rajesh


alfin January 8, 2007 12:11

Re: simulating coanda effect
 
hi rajesh

thanks for your help, i am doing it that way still i haveto refine .....

get in touch with you soon

ALFIN


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