topic Re: Hydrostatic Pressure on the wall of Swimming Pool Open to Air in Inventor Nastran Forum

Hydrostatic Pressure on the wall of Swimming Pool Open to Air

JeffW2026 — Fri, 29 Aug 2025 18:48:06 GMT

I have posts and answers on this topic, but not sure if my situation has been covered and explained. The help only has one example for a liquid in a tank, which does not apply here. I am applying hydrostatic pressure on an acrylic panel that will be set in the wall of a swimming pool, in order to determine the thickness of the concrete and required rebar...SO, I define the hydrostatic pressure on the concrete wall & acrylic panel, the point on the surface, direction where the depth varies, and I add 14.7 psi for atmospheric pressure and get results.

The problem is that I am an order of magnitude greater deflection than the acrylic panel manufacturer. The question is, should the surface pressure be 14.7 psi or 0 psi?

Thank you anyone who can help me understand how the surface pressure is implemented in Nastran.

-Jeff

Re: Hydrostatic Pressure on the wall of Swimming Pool Open to Air

JeffW2026 — Sat, 30 Aug 2025 16:02:25 GMT

Does anybody on the forum know the answer to the question? Should "Surface Pressure" should be 14.7 psi or 0 psi when loading the wall of an outdoor swimming pool?

Thanks,

Jeff

Re: Hydrostatic Pressure on the wall of Swimming Pool Open to Air

John_Holtz — Tue, 02 Sep 2025 22:03:03 GMT

Hi Jeff,

The "Surface Pressure" should be 0 psi. The atmospheric pressure (14.7 psi) is acting on all side and cancels out.

Another way to think of it is this: The water pressure is 0 psi at the top of the fluid and increases as you go down. If you include the atmospheric pressure, the water pressure would start at 14.7 psi at the top of the fluid and increases as you go down.

Hope this leads to more accurate results.

John