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### Normal-Tangential Velocity Rotate = Logical False

Posted: 11 Mar 2016, 16:26
Hi all, I am using a .sif I wrote a couple years ago representing an idealised fjord-like domain, i.e. long and thin with side walls and a grounded and floating part.

I find this rotate line in my sidewall boundary conditions, which I had more-or-less forgotten about over the last two years. Here is an example:

Code: Select all

``````Boundary Condition 1
Name = "sidewall y=yMin"
Target Boundaries(1)  = 1

Normal-Tangential Velocity = Logical True
Normal-Tangential Velocity Rotate = Logical False
Slip Coefficient 1 = Real 10.0
Slip Coefficient 2 = Real 0.00001
Slip Coefficient 3 = Real 0.00001

External Pressure = Variable depth
Real MATC "1.0 * rhoi * gravity * tx"
End
``````
If I remove it then I get ice leaking out of the bottom of my side wall boundaries. But I don't know what it does and I can't find it in the documentation... I guess the rotate command somehow ensures that the normal at the bottom of the side walls doesn't point off at 45 degrees below the horizontal, which I guess would allow the ice leakage. But how exactly? Does it force the whole side wall boundary to have the same normal? Does it only effect the edges of the boundary? I need to understand how this works before I apply it to more realistic cases with less idealised geometry.

Thanks,
Rupert

### Re: Normal-Tangential Velocity Rotate = Logical False

Posted: 05 Oct 2016, 11:51
bump!

Is there a description of this option somewhere? Still not quite sure what it is doing...