Hydrostatic pressure distribution despite fluid motion

[Kqwert]

Hello,

in some exam questions I've looked at it is stated that the pressure distribution is hydrostatic, even though there is fluid motion. (In these cases the velocity has been constant over the section where the pressure is said to be hydrostatic). Is it really possible to assume that the pressure varies hydrostatically when there's fluid motion?

 

[Chestermiller]

If the fluid velocity vector is horizontal everywhere, then it's OK to call the pressure variation in the vertical direction hydrostatic. Otherwise, the pressure should be referred to as "static" pressure or (just plain) pressure.

 

[Kqwert]

If the fluid velocity vector is horizontal everywhere, then it's OK to call the pressure variation in the vertical direction hydrostatic. Otherwise, the pressure should be referred to as "static" pressure or (just plain) pressure.

Thank you, but shouldn't the velocity vector be uniform as well?

i.e

--->
--->
--->
--->

 

[Chestermiller]

Thank you, but shouldn't the velocity vector be uniform as well?

i.e

--->
--->
--->
--->

If the flow is horizontal, then the velocity in the z direction is zero and, from the Navier Stokes equations and the continuity equation, it will be hydrostatic in the z direction.

 

[Kqwert]

If the flow is horizontal, then the velocity in the z direction is zero and, from the Navier Stokes equations and the continuity equation, it will be hydrostatic in the z direction.

Thank you. Do you have any links explaining this?

 

[Chestermiller]

Thank you. Do you have any links explaining this?

Do you have any background on the Navier Stokes equations and the continuity equation, or are you relatively new to fluid dynamics?

 

[Kqwert]

Do you have any background on the Navier Stokes equations and the continuity equation, or are you relatively new to fluid dynamics?

I am familiar with the continuity equation, but not very familiar with Navier Stokes.

 

[Chestermiller]

I am familiar with the continuity equation, but not very familiar with Navier Stokes.

OK. Google the Navier Stokes equations, and examine them for a Cartesian Coordinate system.