Potential flow around a sphere

  • #1
happyparticle
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Homework Statement
Consider the steady flow pattern produced when an impenetrable rigid spherical obstacle is placed in a uniformly flowing, incompressible, inviscid fluid. Find a solution for the potential flow around the sphere.
Relevant Equations
##\nabla^2 \phi = 0##
I tried to find a solution to the Laplace equation using spherical coordinates and the separable variable method. However, I found equations that I simply don't know how to find a solution. Thus, I tried in cylindrical coordinates with an invariance in ##\theta## but now I'm facing this equation.

##\frac{1}{s} \frac{d}{ds}(s \frac{dS}{ds}) = -k^2 S##

Is there a fairly simple solution for it or should I find another way to do this problem?
 
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  • #2
I am not sure to distinguish S and s in your equation. Let me rewrite it with x for s and y for S
[tex]\frac{1}{x} \frac{d}{dx}(x \frac{dy}{dx}) = -k^2 y[/tex]
Is it the right equation which has constant k with its physical dimension of [1/s] ? It belongs to Sturm -Liouville equation whose solutions are Bessel functions.
 
Last edited:

1. What is potential flow around a sphere?

Potential flow around a sphere is a theoretical model used in fluid dynamics to describe the flow of an inviscid, incompressible fluid around a solid sphere. In this idealized scenario, the fluid flow is assumed to be irrotational, meaning that the velocity field can be described as the gradient of a scalar potential function.

2. What are the key assumptions made in potential flow around a sphere?

The key assumptions made in potential flow around a sphere include the fluid being inviscid (no viscosity effects), incompressible (constant density), and irrotational (zero vorticity). Additionally, the flow is assumed to be two-dimensional and steady, with the sphere being of infinite extent in all directions.

3. How is potential flow around a sphere mathematically modeled?

Potential flow around a sphere is mathematically modeled using the Laplace equation for the scalar potential function, subject to appropriate boundary conditions at the surface of the sphere. The flow field can be obtained by solving this partial differential equation using techniques such as separation of variables or complex analysis.

4. What are some important features of potential flow around a sphere?

Some important features of potential flow around a sphere include the formation of a stagnation point at the front of the sphere, the presence of a circulation around the sphere resulting in lift force, and the development of a wake region downstream of the sphere. These features are characteristic of inviscid flow behavior.

5. What are the limitations of potential flow around a sphere as a model?

While potential flow around a sphere provides valuable insights into the flow behavior of inviscid fluids, it has limitations. The model neglects important physical phenomena such as boundary layer separation, viscous effects, and three-dimensional flow structures. As a result, the predictions of potential flow may deviate from experimental observations in certain scenarios.

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