In fluid mechanincs, “sloshing” refers to the (chaotic) movement of liquid (water, fuel, liquid gas etc.) inside a container, that is also moving. In most of the cases, the liquid has a free surface too, so the movement is chaotic, and a multiphase modelling approach is needed. Typical examples are tank sloshing problems, that can be very well simulated with Computational Fluid Dynamics simulations.
The movement of the fluid usually results in internal waves, that causes additional forces and pressures on the wall of the container. Typical example of this is sloshing in road tank vehicles, where the force of the internal moving fuel can influence the stability and braking, and therefore the safety of the truck.
An other interesting topic is fuel nozzle starving, whereas the motion of the liquid in the partially filled tank can cause situations, where the engine does not get enough fuel. Under certain situations, such as strong acceleration, turning or braking, this phenomena can cause serious problems in the fuel system.
Fuel tank sloshing simulation using CFD (Computational Fluid Dynamics)
Fuel movement at 75% capacity in a race car tank
The video above shows how the fuel in a tank moves under a sudden forward acceleration. It is clearly visible that there is a wavy pattern on the surface of the fuel, and also that the main fuel valve on the right (lower bump on the surface) gets fuel all the time.
Let’s see what happens at 25% capacity:
As the fuel tank is not fully filled, the wavy motion of the fluid is stronger. This results in a short starvation of the main fuel nozzle (lower bump on the right side). Further decreasing the fuel level might result in a longer starvation time and therefore engine malfunction.
Tank sloshing in a lateral acceleration situation (sharp turning)
When the vehicle turns sharply, sloshing can lead to malfunction of the engine. Let’s have a look at these scenarios in case of different tank geometries.
If we introduce a baffle in the tank, it certainly helps to block the wave.
The final solution for this project was to place the fuel nozzle to more optimal place and introducing more baffles. I can not present the video here due to confidentiality reasons.
How I can help you with tank sloshing simulations?
If you think a cheap, cost-effective and fast fluid dynamics simulation could help you improve your product like presented above, please contact me. I am offering CFD simulation services on an on-demand basis for tank sloshing simulation projects!