Let's say we have r=R( theta, phi, t) on the surface of the particle and need to find the normal vector in Spherical Coordinate system. We know that, the unit vector =grad(r-R( theta, phi, t)) / |grad((r-R( theta, phi, t))|(adsbygoogle = window.adsbygoogle || []).push({});

where grad is Spherical gradient operator in term of e_r, e_\theta, e_\phi.

Can you please help me to calculate the normal velocity to the surface in Spherical Coordinate system.

Thank for your help.

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# A Normal velocity to the surface in Spherical Coordinate System

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