Integral form of momentum equation

  • #1

Main Question or Discussion Point

Hello guys!
can i get the derivation for this equation ?

upload_2016-6-25_16-1-0.png
 

Answers and Replies

  • #2
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I think the first term should be a partial derivative with respect to time t (not x), and represents the rate of accumulation of x-momentum within the control volume. The second term represents the net rate of x-momentum leaving the control volume.
 
  • #3
I think the first term should be a partial derivative with respect to time t (not x), and represents the rate of accumulation of x-momentum within the control volume. The second term represents the net rate of x-momentum leaving the control volume.
yes sir as you said the 1st term should be the partial derivative with respect to time but i don't know why our teacher in the fluid class wrote the equation in this form, and it was not a mistake because he used it again and again, can you explain the logic behind it as he is a very senior teacher and he wouldn't make such a silly mistake
 
  • #4
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yes sir as you said the 1st term should be the partial derivative with respect to time but i don't know why our teacher in the fluid class wrote the equation in this form, and it was not a mistake because he used it again and again, can you explain the logic behind it as he is a very senior teacher and he wouldn't make such a silly mistake
I stand by what I said. I can't account for what your teacher does. All I can do is confidence in what I am saying.

My questions for you are:

1. How does his equation account for the time rate of accumulation of x momentum within the control volume?

2. When he writes the corresponding equation for the conservation of mass within the control volume, does his equation have a partial derivative with respect to x or a partial derivative with respect to t?
 
  • #5
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Here's a couple of more questions for you:

1. What are the units of the term as your teacher has written it?

2. Are those units of force?
 
  • #6
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So.... What are your answers to my questions?
 
  • #7
sorry i asked him and he said its partial by partial t and not x his writing style is different so i mistakenly wrote it as partial by partial x
 
  • #8
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sorry i asked him and he said its partial by partial t and not x his writing style is different so i mistakenly wrote it as partial by partial x
No problem.
 

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