screen equation notation

ivan-s · December 18, 2014, 15:22

I have encountered the following notation used to describe a screen boundary condition with the k-epsilon model. Here are two example equations.

$k_+ = \eta^2k_-$
$[\rho u \cdot n]^+_- = 0$

In the first equation, it seems to say that k on the upstream boundary (

) would be much larger than k on the downstream boundary (

). This makes sense. The screen has a calming effect on turbulence.

I am unsure of the meaning of the second equation, because I do not know what

means. I don't understand why there should be a + above and a - below. Maybe this is what it means:

,

please let me know. Thank you.

ivan-s · December 19, 2014, 10:49

I have heard from another source that this is a true statement:

That is, the +- after a bracket means the difference of the contents evaluated on both sides of the screen.

December 18, 2014, 15:22	screen equation notation	#1
ivan-s New Member Иван Сташко Join Date: Dec 2013 Posts: 28 Rep Power: 12	I have encountered the following notation used to describe a screen boundary condition with the k-epsilon model. Here are two example equations. $k_+ = \eta^2k_-$ $[\rho u \cdot n]^+_- = 0$ In the first equation, it seems to say that k on the upstream boundary () would be much larger than k on the downstream boundary (). This makes sense. The screen has a calming effect on turbulence. I am unsure of the meaning of the second equation, because I do not know what means. I don't understand why there should be a + above and a - below. Maybe this is what it means: , please let me know. Thank you.

December 19, 2014, 10:49	Yes	#2
ivan-s New Member Иван Сташко Join Date: Dec 2013 Posts: 28 Rep Power: 12	I have heard from another source that this is a true statement: That is, the +- after a bracket means the difference of the contents evaluated on both sides of the screen.

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