How to add Hydrostatic Load
- February 28, 2023
- Jon Duffin
SOLIDWORKS
How to add Hydrostatic Load
To begin our tutorial on How to add Hydrostatic Load, a hydrostatic pressure is the load felt by a surface due to the weight of a fluid. The pressure is not equal at all points however, the pressure increases from zero above the water surface and increases as you go deeper into the fluid. Here are the basic steps to accurately add a hydrostatic load to your simulation study:
- Split the faces of your model at the liquid interface
- Add a reference coordinate system to the top of the liquid interface with one axis pointing in the direction of gravity
- Add a Pressure Load to all faces of your model that touch the liquid and apply the “Nonuniform” option using the previously defined coordinate system, the density of your liquid, and the gravitational constant.
We will go through these steps using a classic 5 gallon bucket filled with water as an example. Note: there are multiple ways to perform these steps to get to the same result, but I find this the easiest to comprehend.
- Split the faces of your model at the liquid interface
Create a Reference Plane at the location of the water interface
Launch the “Split Line” command. Use the intersection method and select the created plane and the face to be split
The faces should now be split to allow selection in the simulation setup.
2. Add a reference coordinate system to the top of the liquid interface with one axis pointing in the direction of gravity.
When adding the coordinate system, it doesn’t matter where it is located as long as it lies on the interface of the top of the liquid (The plane created in step one).
Start a sketch on the plane created in step one and draw a sketch point where you want the coordinate system (again, location shouldn’t matter as long as you started the sketch on the correct plane) and confirm the sketch
Create the reference coordinate system and use the sketch point previously created for “Position” reference and in the “Z axis” section select the plane created in step 1 (to give a direction for gravity that will be used later on)
3. Add a Pressure Load to all faces of your model that touch the liquid and apply the “Nonuniform” option using the previously defined coordinate system, density of your liquid, and gravitational constant.
Add a pressure load
Select all faces that touch the liquid and keep the “Normal to selected face” option Selected. You can select all of the faces in a single Pressure Load command
In the “pressure value” section, you will want to check your units and enter in the value of the gravitational constant times and density of your liquid. In this case, we have water at sea level, so we will enter 9810 (1000 for water and 9.81 at sea level on earth for gravity). (Note: that if you do a unit’s analysis on density times
Gravity it is instead of but in the next step, when we add in the water height, the units will work out correctly)
Now check the “Nonuniform Distribution” option and select the coordinate system previously defined in step 2.
In the Nonuniform Distribution Section, make sure the units match the units used to enter the pressure value (eg. If you have , select or if you have select ) and select “Edit Equation”
Identify which direction corresponds to your direction of gravity and add a “0*” in front of every dimension except for the direction of gravity from your coordinate system. For example, in our case the coordinate system has the Z axis in the direction of gravity so I will enter 0*”x” + 0*”y” + “z”. The actual pressure that will be applied to the simulation will be the pressure value, that you entered in the property manager previously, times the evaluated value in this equation box. (eg. for a height of 0.1 meters the pressure value will be (0 + 0 + 0.1) * 9810 = 981 at that location.
As a side note, if the top of liquid isn’t free to air then you could add the depth to this equation (eg. If it starts 100 meters below the surface of the ocean and your units were set to meters then for the equation you could enter 0*”x” + 0*”y” + 100 + “z”.)
Double check that the arrows in the view port are slowly getting bigger as you get further down the model and if needed toggle the “reverse direction” button to ensure that the pressure is applied outwards. After that you are good to go with applying a hydrostatic pressure to your simulation!
SOLIDWORKS Simulation Training
If you are interested in learning more about Simulation, consider taking our 3-day training course designed to help give you the confidence and skills to accurate run linear static simulations on your own: SOLIDWORKS Simulation Course
SOLIDWORKS Technical Support
You can also contact us about Training or get help from our team by Calling us at 800-364-1652, Emailing us at solidworkssupport@mlc-cad.com, or Clicking here for SOLIDWORKS Technical Support.
About the author
Jon Duffin is a SOLIDWORKS Technical Support Expert based in the Atlanta area. Prior to his career at MLC CAD Systems, he worked in the defense industry improving the manufacturing processes for Solid Fuel Rocket Motors. He immensely enjoys helping others improve their SOLIDWORKS productivity because it combines his love of engineering with the desire to help other people.
