Pressure gradient in a sphere

  • #1
Have cylinder made from semipermeable material .There is positive pressure inside cylinder and negative pressure outside cylinder .How gradient of pressure will be changed if we convert from cylinder t o sphere?
Thank you
 

Answers and Replies

  • #2
Delta2
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I guess this is a fluid dynamics problem, @Chestermiller could have a look at this but I think you should give us a diagram or an image. I believe the crucial piece of information we are missing is how is the fluid flow outside and/or inside the cylinder or the sphere.
 
  • #3
jbriggs444
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Have cylinder made from semipermeable material .There is positive pressure inside cylinder and negative pressure outside cylinder .How gradient of pressure will be changed if we convert from cylinder t o sphere?
Thank you
I take it that this shell, whether cylinder or sphere, is of non-negligible thickness and that this thickness is the same for the two situations. I also take it that the pressure difference across the shell is also identical in the two cases.

One would further assume that the diffusion rate through an infinitesimal thickness of shell is in proportion to the pressure gradient across that thickness.

In the case of a cylinder, one can see that to maintain a constant flow rate through all of the concentric shells, the pressure profile across the shell must decrease in proportion to the radius. In the case of a sphere, it must decrease in proportion to the square of the radius.

Have you computed the pressure gradient as a function of radius for the cylindrical situation yet?
 
  • #4
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Have cylinder made from semipermeable material .There is positive pressure inside cylinder and negative pressure outside cylinder .How gradient of pressure will be changed if we convert from cylinder t o sphere?
Thank you
What research have you done so far regarding the fundamentals of (presumably aqueous electrolyte) solution flow and pressure drop through semipermeable membranes?
 
  • #5
Average trans membrane pressure in this situation is about 100-150 mm Hg .I am just testing hypothesis and didn't do any preliminary research.What info could be utilized?
Thank you very much
 
  • #6
20,877
4,549
Average trans membrane pressure in this situation is about 100-150 mm Hg .I am just testing hypothesis and didn't do any preliminary research.What info could be utilized?
Thank you very much
Not so fast. We're not going to spoon feed this to you. What is the basic equation for the osmotic pressure difference when there is no flow? You are going to have to do some research on your own first before we are willing to help you.
 

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