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June 13, 2014, 16:19 
How can I get the Total Kinetic Energy of Fluid?

#1 
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Subodh
Join Date: Sep 2013
Location: Canada
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Hi,
I would like to know how can i get the total Kinetic Energy of the fluid ,which is being disturbed by an object moving solely due to buoyancy. I need Total K.E at each time interval to determine the added mass as the object moves through the fluid along z axis. Thanks 

July 5, 2014, 22:39 

#2 
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Jeff Burnham
Join Date: Apr 2010
Posts: 204
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I think you need:
Analyze > Probe > General History Data > MassAveraged Mean Kinetic Energy, and select Text as output type at the bottom. This is the kinetic energy corresponding to the mean (nonturbulent) velocity. Remember that velocity can be thought of as a timeaverage mean component + a fluctuating component; this variable is the timeaverage mean only. It's massaveraged by summing the K.E. in each cell x the mass of fluid in that cell and dividing the sum by the mass in all cells. MKE = sum(KEi * mi)/sum(mi) for cells i = 1 to n MassAveraged Turbulent Kinetic Energy works the same way for the fluctuating velocity component (if you're using a RANS turbulence model like RNG). 

July 6, 2014, 12:43 

#3 
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Subodh
Join Date: Sep 2013
Location: Canada
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Thanks a lot Jeff for reply,
I am using RNG model , but in my General history data I can see "Estimated mean kinetic energy" is it the same as MassAveraged Mean Kinetic Energy? Also while going through the theory of RANS turbulence model I found that the instantaneous kinetic energy k(t) of a turbulent flow is the sum of "Mean kinetic energy " and "Turbulent kinetic energy " So from Flow3d General history data ,can I use "Estimated Mean Kinetic energy +Average Turbulent Kinetic Energy" so as to get the instantaneous Kinetic Energy ? Thanks 

July 6, 2014, 14:29 

#4 
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Jeff Burnham
Join Date: Apr 2010
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That sounds right. I'm not familiar with the 'estimated mean kinetic energy' output. It might be that you're using an older version than I'm familiar with. If the definition is the same, then yes, you can combine MKE and TKE to get the total KE.


July 6, 2014, 14:39 

#5 
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Subodh
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Location: Canada
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Thanks ,
I am using Flow3d 10.0.3.1 Version.. 

July 6, 2014, 15:01 

#6 
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Subodh
Join Date: Sep 2013
Location: Canada
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Also Is it possible to calculate the forces due to collision between two objects inside fluid while using GMO model.
In my case its a underwater spherical ice model hitting a floating platform. In General History data output I can see pressure force and shear force output. Does that includes the impact force due to collision of two bodies too or is it just pressure due to the fluid flow created by moving object ? 

January 26, 2017, 03:30 

#7 
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jadhav sarika
Join Date: Jan 2017
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What is the meaning of estimated mean kinetic energy in flow 3d and what location it is calculated in stepped spillway.


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