Simulating Hydrostatic Pressure on Vessel Structures

Tips & Tricks

A fluid with a constant density in a homogenous gravitational field exerts a hydrostatic pressure on its surrounding container walls according to Pascal's law.

p(h) = ρ ∙ g ∙ h


p(h)  is the hydrostatic pressure depending on the height of the fluid level in [N/m²]
ρ  is the density in [kg/m³]
is the acceleration due to gravity in [m/s²]
is the height of the fluid level in [m]

This loading can be simulated very efficiently in RFEM, for example by using free rectangular loads.

The free rectangular load is a surface load function used for the definition of compressive loads on surfaces. The tributary area of this particular load type is defined by a cuboid hovering freely in space. Thus, only those assigned surface areas are loaded that are located within the spatial cuboid boundary. The spatial cuboid boundary is defined in the program by two points which raise a projection plane between the global coordinate axes. Thus, this projection plane is the side view of the cuboid boundary. The length of the cuboid boundary is not defined and is determined by the assigned surfaces directly.

The simulation of a hydrostatic pressure requires that the pressure is exerted on each point of the vessel perpendicularly to the walls and increases linearly with the distance to the fluid level according to the law described above. To achieve an effect perpendicular to the walls, select the load direction z ‘Local - with respect to the true area’. The linear distribution depending on the fluid level is simulated by switching to a linear load distribution in the respective direction and the assignment of the load ordinates at the definition points of the projection plane (above - zero, below - value according to expression).

To simulate different fluid levels very quickly, change the definition point p1 of the projection plane above and the load ordinates at location p2.


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RFEM 5.xx

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Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements