To perform a similar analysis of a fluid that is fully enclosed within a solid container, consider the following hints and recommendations:
Verify the fluid elements.
After creating the fluid elements (ESURF), note whether they have positive or negative volumes. Fluid elements have negative volumes if nodes are ordered in a clockwise direction, or if the normal of the container is oriented outward from the pressure node.
Introduce the fluid mass based on the volume of the fluid element.
Set KEYOPT(5) = 1 for the hydrostatic fluid. No mass is added if the volume becomes negative.
Specify the fluid compressibility type.
Set KEYOPT(6) = 0 for the hydrostatic fluid to model compressible fluid (default), or KEYOPT(6) = 1 to model incompressible fluid.
Determine the pressure node location carefully.
The pressure node can be located anywhere within the fluid volume. If the fluid volume is bounded by one or more symmetry lines or planes, however, the pressure node must be on the line or plane of symmetry, or on the intersecting corner or line of multiple symmetry lines or planes, and it must have symmetrical boundary conditions.
Use impact constraints appropriately.
For contact, specify impact constraints (KEYOPT(7) = 4). This option includes automatic time-increment adjustments for standard (default) or rough contact (KEYOPT(12) = 0 or 1, respectively) in a transient dynamic analysis.
Display the reinforcing elements.
To display the reinforcing elements, issue the following commands:
/psymb,layr,1 /device,vector,1