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Old   February 11, 2013, 09:56
Default Introducing normalized velocity
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Govindaraju
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Dear friends
I would like to introduce normalized velocity profile as an input. The velocity changes with respect to time under different condition. So I did normalized the data (0 to 1).
Now the output data has no unit ( assume I am correct). How to introduce this normalized data to the input boundary condition in the velocity field?

Thank you for your kind attention

Regards

Govind
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Old   February 11, 2013, 18:15
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Glenn Horrocks
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Velocity boundaries need an input in units of length/time, so you just need to un-normalise it.

Alternately you can trick CFX into using non-dimensional inputs providing you work the unit change through all units in the simulation and end up with a consistent set of units (which are actually unitless ). Using this you can do non-dimensional simulations in CFX.
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Old   February 11, 2013, 23:53
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Quote:
Originally Posted by ghorrocks View Post
Velocity boundaries need an input in units of length/time, so you just need to un-normalise it.

Alternately you can trick CFX into using non-dimensional inputs providing you work the unit change through all units in the simulation and end up with a consistent set of units (which are actually unitless ). Using this you can do non-dimensional simulations in CFX.
Dear Mr. Glenn

That means I have to choose simply all the dimensionless number to velocity unit. Am I correct?

If this is the case, the maximum velocity becomes 1 m/s and minimum velocity becomes 0 m/s.

in my data at t=0, the normalized value is 0.7070 . this value corresponds to
0.2375 m/s ( un normalized value).

In a global initialization, what is the initial value at t= 0 s? . Is it 0.7070 or 0.2375?
( I put at t=0, velocity 0.7070 m/s).

If I use normalized value , one simulation is sufficient. Am I correct?

If I want to change the input parameter for the next result, what is the procedure?

( Note: If I use normalized method other set of readings also traces the same value )


Thank you

Regards

Govind
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Old   February 12, 2013, 07:08
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No matter what you do the unit system you use has to be consistent.

It can either be a non-dimensional scheme or a quasi-dimensional scheme (simply un-normalising your velocities). What is the best approach will depend on what information you know and what you are trying to achieve.
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Old   February 12, 2013, 07:26
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Quote:
Originally Posted by ghorrocks View Post
No matter what you do the unit system you use has to be consistent.

It can either be a non-dimensional scheme or a quasi-dimensional scheme (simply un-normalising your velocities). What is the best approach will depend on what information you know and what you are trying to achieve.
Thank you Mr Glenn
I will try my best

Regards

Govind
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Old   February 19, 2013, 00:18
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Quote:
Originally Posted by ghorrocks View Post
Velocity boundaries need an input in units of length/time, so you just need to un-normalise it.

Alternately you can trick CFX into using non-dimensional inputs providing you work the unit change through all units in the simulation and end up with a consistent set of units (which are actually unitless ). Using this you can do non-dimensional simulations in CFX.

Dear friends

I have an CEL expression for velocity U(t)= U(max)[1+sin (4*pi*f*t- (pi/2))]

for my simulation I want to change U(max ) everytime.

If I convert into normalized, I got a same curve for all the U(max) values.

Now, is there any way to proceed with single simulation and get multiple results for different U(max) values?

Regards

Shashwat
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Old   February 19, 2013, 04:58
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Do you want to see the result for a series of U(max) values in a steady state simulation? The best way to do this is to either script up a series of steady state runs, possibly using other runs as intial conditions to speed sonvergence; OR use a multiple configuration def file to do multiple setups OR use workbench to do a parametric sweep.

There's three ways of doing it, you choose the one you like the best.
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Old   February 19, 2013, 22:02
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Quote:
Originally Posted by ghorrocks View Post
Do you want to see the result for a series of U(max) values in a steady state simulation? The best way to do this is to either script up a series of steady state runs, possibly using other runs as intial conditions to speed sonvergence; OR use a multiple configuration def file to do multiple setups OR use workbench to do a parametric sweep.

There's three ways of doing it, you choose the one you like the best.
dear friend
No my simulations are transient simulation.
can you please explain bit.

I thought in the following way,please correct me if I am wrong.

the normalized velocity curve is simillar for the series of U(max).so find the normalized factor . DO one simulation un-normalized velocity as an input and find the result in cfx post.
If I want to do series of u (max) , can I simply multiply with normalized factor?.simillary ,can I multiply the normalized factor with result in cfx post?.
is the way correct ?

Thank you

Regards
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