What does the snGrad operator do?

Verse · August 11, 2016, 09:59

I noticed that fvc::grad(U) gives a 2nd order tensor with the derivative of U with respects to each of the 3 coordinates, but what exactly does snGrad do? It gives a vector with 3 components, and I don't quite know what those 3 components mean.

Thank you!

anishtain4 · August 11, 2016, 12:09

Source code is your best friend when such questions come up.
snGrad calculates the surface normal gradient for you. Since the surface normal is only one direction, you will get one component for every component of velocity. However if you input a scalar field, you will get only a scalar. So the output really depends on the input.

fluidflowsteel · January 6, 2017, 06:23

Hi ,

I have a variable p for which I want to calculate the gradient normal to the surface in both x and y directions. Can anyone help me ?

With regards

August 11, 2016, 09:59	What does the snGrad operator do?	#1
Verse New Member Dominic Join Date: May 2016 Posts: 27 Rep Power: 9	I noticed that fvc::grad(U) gives a 2nd order tensor with the derivative of U with respects to each of the 3 coordinates, but what exactly does snGrad do? It gives a vector with 3 components, and I don't quite know what those 3 components mean. Thank you! Luttappy and linyanx like this.

August 11, 2016, 12:09		#2
anishtain4 Senior Member Mahdi Hosseinali Join Date: Apr 2009 Location: NB, Canada Posts: 273 Rep Power: 18	Source code is your best friend when such questions come up. snGrad calculates the surface normal gradient for you. Since the surface normal is only one direction, you will get one component for every component of velocity. However if you input a scalar field, you will get only a scalar. So the output really depends on the input. tariq, ashish.vinayak, nvnkush and 2 others like this.

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January 6, 2017, 06:23		#3
fluidflowsteel New Member fluidflowsteel Join Date: Jun 2016 Posts: 21 Rep Power: 9	Hi , I have a variable p for which I want to calculate the gradient normal to the surface in both x and y directions. Can anyone help me ? With regards