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March 6, 2021, 18:26 |
Meaning of Mass Flow Density
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#1 |
Senior Member
Kira
Join Date: Nov 2020
Location: Canada
Posts: 435
Rep Power: 9 |
Hello Everyone,
I was looking for an explanation for the meaning of mass flow density. There is only one post on this website back from 2004 that is unanswered. I would like to re-ask it, this time with my hypothesis of what it would be at the bottom. For reference, the Function Calculator in the Post-processor calculates the following: Function: MassFlowAve Location: Inlet Variable: Particle.MassFlowDensity What is it actually calculating? I looked in the CFX-Post User's Guide, but while it mentions it can calculate it, it does not provide a description. The units of mass flow density are [kg m^-2 s^-1], mass flow rate is in [kg s^-1], and energy density is [kg m^-1 s^-2], so would it be something related to the energy the particles carry with them? From the energy density units, I see I would need another m^-1 s^1. If I were to use the mass flow rate, I would need a [m^-2]. |
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March 6, 2021, 19:50 |
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#2 |
Super Moderator
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,427
Rep Power: 49 |
I don't see how energy density comes into this.
From your description, Particle.MassFlowDensity with the unit of is just that: the mass of particles passing through an area per second. Plugging this quantity into a "mass flow average" function for a surface should not change the units. It calculates the average of the Particle.MassFlowDensity, weighted by mass flow rate. |
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March 6, 2021, 21:33 |
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#3 |
Senior Member
Kira
Join Date: Nov 2020
Location: Canada
Posts: 435
Rep Power: 9 |
Quote:
Thank you very much for your answer, makes sense to me now. I was just trying to determine the physical meaning of mass flow density and was probably over-thinking it a bit. |
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March 7, 2021, 05:52 |
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#4 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,893
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kg/(m^2*s) =(kg/m^3)*(m/s)
If I am right, the quantity could be seen as rho*u, that is a momentum quantity |
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March 7, 2021, 11:43 |
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#5 | |
Senior Member
Kira
Join Date: Nov 2020
Location: Canada
Posts: 435
Rep Power: 9 |
Quote:
Ah, right! This was more like what I was trying to figure out. Thank you for handing me this piece of the puzzle, I think it was what I was looking for. |
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cfd-post, mass flow density, parameter |
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