Boundary conditions for fluid flow

AI Thread Summary
Boundary conditions for nonviscous, incompressible fluid flow indicate that the radial velocity at the surface of a sphere does not necessarily vanish, challenging typical expectations. The discussion references the continuity of velocity components, drawing parallels to magnetostatics where div B = 0 ensures continuity of B-perpendicular. For an infinite plane, the expectation is that velocity would vanish at the surface, aligning with the no-slip boundary condition. The mathematical expressions provided confirm that the radial component does approach zero at the surface of the sphere under specific conditions. Overall, the analysis highlights the complexities of fluid dynamics at boundaries.
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What are the general boundary conditions for nonviscous, incompressible fluid flow? I am trying to find the velocity of fluid at the surface of a sphere with the incident fluid having uniform velocity. I am surprised to find in the solution that the radial velocity at the surface does not vanish. For magnetostatics, div B = 0 implies B-perp is continuous. Would not div v= 0 imply the same for v-perp?
What about the same problem but incident upon an infinite plane? Would the velocity not vanish at the surface?
 
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I gather you are asking about the no-slip boundary condition?
 
From Fluid Mechanics by Frank M. White

\psi = -\frac{1}{2} U r^2 sin^2 \theta + \frac{\lambda}{r} sin^2\theta

\psi = 0 => r = a = (\frac{2\lambda}{U})^{1/3}

v_r = -\frac{1}{r^2 sin\theta} \frac{\partial \psi}{\partial \theta}

v_r = U cos\theta (1 - \frac{a^3}{r^3})

so the radial component does appear to vanish at the surface r = a
 
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