Current Velocity 1

[teb1]

I am trying to model a retaining wall. The static hydrostatic pressure against the wall is easy to model and simulate. But!, does anyone have good rule of thumb for modeling the pressure developed due to say a 5mph current pushing against the retaining wall.

Thanks in adance.

Tommy

 

[btrueblood]

For a perpendicular current, add the dynamic pressure, q:

q = 1/2 * rho * V²

rho is mass density (kg/m²), V is velocity (m/s).

 

[teb1]

A belated thank you very much.

Tommy

 

[gwolf]

rho should be in Kg/m3 not Kg/m2 - if you're not convinced do a 5 line dimensional analysis.

 

[teb1]

Thanks,

I caught the dimensional error, I'm sure it was tipograpnical error, when I converted the units to lb/in3 and ft/sec.

 

[rb1957]

teb1 ...

make sure you're using MASS density (slug/ft3) rather than the more common weight denisty (lbf/ft3) ...

slug/ft3 = lgf/ft3 / g

 

[teb1]

Thanks,

I'll have to go back and check that.

teb

 

[teb1]

Thanks

I did convert the weight density to mass density.

Regards,

teb

 

[btrueblood]

Oy. When doing these calc's. I always convert to SI, in order to keep my units straight, then convert back to English units.

 

[gwolf]

I'm staggered by the way Americans doggedly persist in using archaic unit systems for high technology, often international designs. These systems which you use make your lives a lot harder than is necessary and can lead to serious mistakes. Weight density, mass density - all confusion, and all so unnecessary. In SI density is just what it says on the box. If you want to buy fuel, or vegetables then imperial units are fine but please drop it from aerospace. In fact I feel a thread coming on.....

 

[teb1]

Dogged persistance has gotten me where I am today and I couldn't be happier. Most of the individuals that I work with everyday (welders and machinist) in the southern U.S., can't or won't grasp the concept of a kilogram or a meter in their everyday life.

I deal in metric or SI if you will, when I have to, but I am more confortable with english units.

teb1