Fluid Mechanics local acceleration and convective acceleration


by yrael
Tags: acceleration, convective, fluid, local, mechanics
yrael
yrael is offline
#1
Feb10-08, 06:29 PM
P: 7
1. The problem statement, all variables and given/known data
The velocity of the water in the pipe is given by v1=.5t m/s and v2=1tm/s, where t is in seconds. Determine the local acceleration at points 1 and 2. Is the average convective acceleration between these two points negative, zero, or positive?



2. Relevant equations

A figure of pipe (funnel like) that is larger at the input end with v1 and smaller end with out put speed of v2.



3. The attempt at a solution

I don't really know how to start answering this question, I don't have the text with me (still in delivery) and don't have any notes thats on this topic.

My try: d (v1)/dt=0.5t so a=d(v1)/dt=.5 m/s^2
d(v2)/dt=1t so a2=d(v2)/dt=1 m/s^2
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Shooting Star
Shooting Star is offline
#2
Feb11-08, 03:24 PM
HW Helper
P: 1,986
The local accn changes because the flow is not steady and time dependent, and the values are as you have derived.

The convective accn is positive because a particle of fluid has to speed up due to the area at point 2 being smaller than area at point 1.

For a steady flow, there would be convective accn only.


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