Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

1-dimensional flow is when velocity is in 1 direction only.

Ref: R.K. BANSAL.

A flow, in which the streamlines of its moving particles are represented by straight line, is called one-dimensional flow.

Ref: R.S KHURMI & J.K.GUPTA.

Option D is correct. Option B is the subset of option D. Because a Straight Line path and a zig-zag path both can be one Dimension.

I agree @Aman.

The one-dimensional flow does not necessarily mean a straight line.

Suppose an ant is moving in a zig-zag path. If we look at the path of an ant from above we will observe ant is moving in a zig-zag path which is lying on a 2d plane but if you ask the ant what is the path of your motion? The ant will definitely say that I am is moving in a straight line. Because ant will not be able to observe its motion from above. As soon as the ant takes turns on its path its X coordinate will also take a turn with it (ant). So if you are moving in a zig-zag path you can not say that you are moving in 2d. It will be ond D only.

No, the One-dimensional flow has nothing to do with the straight line or curve. If the entire flow parameter requires only 1 independent variable to completely specify the flow then it is called one dimensional.

B, right because we considered fluid is non viscous in nature and PV graphs show straight line, PV ' constant.

Option B is not correct because flow in a straight line is called laminar flow.

Option D is correct.

Both B & D are correct as if the flow is one dimensional it will flow in a straight line. As one dimension always represents a single coordinate, i.e., U=f(x) if we consider flow along the x direction. But this explanation follows option D too as if the flow is considered along line x=y then with respect to the coordinate system which is tilted by 45 degrees it is a flow along the axis and hence again in a straight line.

So the velocity will be given as U=f(x') where x' would be the x direction in transformed axis and hence flow in a single direction is also a one-dimensional flow.

One dimensional flow mean the flow which is in a straight line.

Answer B is correct.

Answer will be D.