- #1
MacLaddy
Gold Member
- 291
- 11
Hello folks,
I am having difficulty comprehending some material in my fluid dynamics course. This is not a homework question, just something missing in my understanding.
When proving the "Pressure Field Equation," (something I am not yet able to do) there is a series of steps my instructor took.
[itex]P=P_1+\Delta{P}[/itex]
[itex]P=P_1+\Delta{y}\frac{dp}{dy}[/itex]
Which somehow, magically, leads to...
[itex]F_y = (P+\frac{\partial{p}}{\partial{y}}\frac{\delta{y}}{2})*\delta{x}\delta{z}[/itex]
So my question is this.
[itex]\frac{dp}{dy}[/itex] is simply the change of P wrt y
[itex]\frac{\partial{p}}{\partial{y}}[/itex] is the change of p wrt y in a particular direction, or part of the gradiant.
But what in the sam is [itex]\frac{\delta{y}}{2}[/itex]?
Why the delta?
Any help would be appreciated.
Thanks,
Mac
I am having difficulty comprehending some material in my fluid dynamics course. This is not a homework question, just something missing in my understanding.
When proving the "Pressure Field Equation," (something I am not yet able to do) there is a series of steps my instructor took.
[itex]P=P_1+\Delta{P}[/itex]
[itex]P=P_1+\Delta{y}\frac{dp}{dy}[/itex]
Which somehow, magically, leads to...
[itex]F_y = (P+\frac{\partial{p}}{\partial{y}}\frac{\delta{y}}{2})*\delta{x}\delta{z}[/itex]
So my question is this.
[itex]\frac{dp}{dy}[/itex] is simply the change of P wrt y
[itex]\frac{\partial{p}}{\partial{y}}[/itex] is the change of p wrt y in a particular direction, or part of the gradiant.
But what in the sam is [itex]\frac{\delta{y}}{2}[/itex]?
Why the delta?
Any help would be appreciated.
Thanks,
Mac