# Corresponding Pressure gradient with flow velocity

Tags:
1. Jan 14, 2016

### Mazzletov

I have some questions concerning hydraulic engineering. I'm currently working an simulating laminar flow.
This laminar flow is induced by a pressure gradient. The assumed length is 1 meter, therefore the pressure gradient is equal to the actual pressure in reference with zero.

What are typical pressure gradient used in flow? I'm not certain but I think the imposed pressure gradient has units N/m². So typical values are around 1 N/m² to impose flow or am I wrong about this?
On the other hand, I'm working on oscillating waves. These wave are characterised by a certain period T and velocity amplitude. The corresponding pressure gradient can be found using the velocity gradient.

∂P(osc)/∂x = -ρw*∂u(osc)/∂t

The oscillating flow is described as with t, the time step and the density of water ;

u(osc) = U(ampl)*cos(2*π*t/T)
∂P(osc)/∂x = ρw*U(ampl)*2*π/T

If the amplitude of the velocity U(ampl) is equal to 1,5 m/s. What would my pressure gradient be equal to? I'm a little bit confused because I find a pressure gradient of 1308 kg/(m²s²) but I think I did something wrong.

Many thanks

2. Jan 14, 2016