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Normal vector to a selected boundary

Posted Nov 3, 2023, 6:04 p.m. EDT Computational Fluid Dynamics (CFD), Geometry, Material Models 2 Replies

Adebayo Sadiq
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Hi ALL,

What is the expression for the normal vector to a selected boundary? For instance, I tried plotting the velocity vector normal to a selected boundary using (v.nx)>0 to represent y-component velocity in the upward direction but I did not get the expected result.

Thank you.

2 Replies Last Post Nov 6, 2023, 7:08 p.m. EST
Robert Koslover Certified Consultant
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Posted: 12 months ago Nov 3, 2023, 7:10 p.m. EDT
Updated: 12 months ago Nov 3, 2023, 7:10 p.m. EDT

The normal vector on the surface is given by . If you have a vector field given by , then the component of that field that is along the normal to the aforementioned surface is given by its scalar product with that surface normal vector, i.e., . (In 2D, use two components instead of three.)

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The normal vector on the surface is given by (nx,ny,nz). If you have a vector field given by (Vx,Vy,Vz), then the component of that field that is along the normal to the aforementioned surface is given by its scalar product with that surface normal vector, i.e., nx*Vx+ny*Vy+nz*Vz. (In 2D, use two components instead of three.)
Adebayo Sadiq
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Posted: 12 months ago Nov 6, 2023, 7:08 p.m. EST
Updated: 12 months ago Nov 6, 2023, 7:07 p.m. EST

The normal vector on the surface is given by (nx,ny,nz). If you have a vector field given by (Vx,Vy,Vz), then the component of that field that is along the normal to the aforementioned surface is given by its scalar product with that surface normal vector, i.e., nxVx+nyVy+nz*Vz. (In 2D, use two components instead of three.)

Thank you so much! This perfectly solved my concern.

>The normal vector on the surface is given by (nx,ny,nz). If you have a vector field given by (Vx,Vy,Vz), then the component of that field that is along the normal to the aforementioned surface is given by its scalar product with that surface normal vector, i.e., nx*Vx+ny*Vy+nz*Vz. (In 2D, use two components instead of three.) Thank you so much! This perfectly solved my concern.

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