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February 11, 2013, 08:56 |
Introducing normalized velocity
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#1 |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
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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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February 11, 2013, 17:15 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,701
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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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February 11, 2013, 22:53 |
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#3 | |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
Quote:
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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February 12, 2013, 06:08 |
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#4 |
Super Moderator
Glenn Horrocks
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Location: Sydney, Australia
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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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February 12, 2013, 06:26 |
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#5 | |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
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Quote:
I will try my best Regards Govind |
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February 18, 2013, 23:18 |
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#6 | |
Senior Member
Shashwat
Join Date: Nov 2011
Posts: 107
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Quote:
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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February 19, 2013, 03:58 |
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#7 |
Super Moderator
Glenn Horrocks
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Location: Sydney, Australia
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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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February 19, 2013, 21:02 |
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#8 | |
Senior Member
Shashwat
Join Date: Nov 2011
Posts: 107
Rep Power: 14 |
Quote:
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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April 10, 2024, 03:51 |
normalized velocity
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#9 |
New Member
prashant godse
Join Date: Jul 2023
Posts: 10
Rep Power: 2 |
how to calculate normalized velocity and normalized helicity in cfx if any cel expression or somthing that would of great help. i am trying to visualized secondary flow in rotor 67
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April 10, 2024, 04:30 |
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#10 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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Define a new variable in CFD-Post with the normalisation function you want to use. So do this in the post-processor, not the solver, if at all possible.
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Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
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April 10, 2024, 04:36 |
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#11 |
New Member
prashant godse
Join Date: Jul 2023
Posts: 10
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ok got it, i have another question like for normalised velocity i need to find averaged streamline velocity at 99% span. i have created a turbosurface with 99% span how can i calculate averaged velocity
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April 10, 2024, 04:45 |
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#12 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,701
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Have you done the CFD-Post tutorials? That is the best way to learn the capabilities of the software and how to do it.
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Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
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April 10, 2024, 04:47 |
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#13 |
New Member
prashant godse
Join Date: Jul 2023
Posts: 10
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ok will check for it. thanks
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