# Difference between 1D, 2D and 3D Flow

by amck
Tags: 1d flow, 2d flow, 3d flow, difference, flow
 P: 3 Hey guys, I'm new to this forum and was hoping to get a clear answer regarding the difference between 1D, 2D and 3D flows in hydraulics (ex. 2D Numerical Model...) ? Thanks a bunch! -A.
 P: 1,437 It usually refers to the number spatial (or time) dimensions over which the flow variables vary in a given situation or problem.
 P: 3 Thanks for the response! So if you say 2D flow - it's the flow in a plane whereas 1D would be linear?
P: 1,437

## Difference between 1D, 2D and 3D Flow

Pretty much, though a 1D flow would be awfully uninteresting. A 2-D flow may also arise if, say, the flow is axisymmetric.
 P: 3 Fair enough. What kind of "real-life" flow would be considered axisymmetric?
 P: 1,437 The flow around a cone at zero angle of attack, the flow around the Apollo space capsule if it is at zero angle of attack the flow around the front end of a missile, the flow around a non-rotating sphere (in the Stokes limit), and the flow out of a rocket engine would all be examples of axisymmetric flows.

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