How do you calculate the Reynolds Number for a non-spherical object?
- Thursday Nov 5,2009 02:35 AM
- By diddy
- In Others
I have the density (?) of the particles, the fluid, as well as the complete dimensions of the non-spherical particles. I know the Force of drag (F) and the Coefficient of drag (C). But how do you get the Reynolds number from this? I can’t use Stokes’ equations because they only apply to spheres.
Coefficient Of Drag, Density, Drag Coefficient, Reynolds Number, Spheres, Spherical Object, Spherical Particles
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Reynolds number, Re = ?vL/?
where ? is the mass density of the fluid, v is the relative velocity object-fluid, ? is the dynamic viscosity of the fluid, and L is a characteristic length of the object (it is the most significant length that creates the drag).
The drag force equation:
F = q C Sref
where C is the coef. of drag, Sref is the reference area of the object (the area that you used to obtain the coef. of drag), and q is the dynamic pressure. From this equation, knowing F, C and Sref, you can obtain the dynamic pressure, q.
The equation of dynamic pressure is given by:
q = 0.5 x ? x v^2
Knowing q and ?, you can obtain v (velocity). You use this value of velocity to calculate the Reynolds number above (knowing ?, L and ?).
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