Laminar vs Turbulent (K-omega SST)
Figure 1: Showing a comparison between laminar assumption and turbulent assumption with two different initial turbulent conditions, initial conditions were found to be insignificant in terms of results
Figure 2: This time step shows a major difference in results between the two assumptions
Different results are expected from a higher quality mesh visually as we would have a more definite boundary between phases, however, we should also look at the forces put on the tank internally to determine how much the mesh effects the physical results.
Figure 3: Visual comparison of result between Medium mesh (left) and coarse mesh (right)
Figure 4: Comparison of total force in the X and Y directions for both Coarse and Fine grids, showing good overall Agreement
Figure 5: A visualisation of turbulence development in the sloshing cycle with supporting visualisation of the sloshing fluid as a volume rendering
From these results, it can be seen that good general agreement in result between Coarse and Medium results can be seen up until about 2 seconds (Figure 4). Hereafter, the flow becomes more turbulent (Figure 5) and from there on a difference in results is present (Figure 4), particularly in the amplitude of the forces where the final negative oscillation has a difference of almost 10N.
Stress on the Fuel Sender
If we were to look at the design of the fuel sender to reduce its probability of failure or malfunction we would need to start by checking how it performs under sloshing of the fuel. Sloshing although unlikely to yield the material it will certainly put stress on the sender periodically depending on how the vehicle is travelling. High constant speed is unlikely to cause much fatigue. however, lowerspeed country road driving is likely to slosh more and cause more stress and more cycles thus fatiguing the structure more.
Figure 6: A visualisation of von Mises stress and scaled deformation, in time with fluid sloshing with velocity vectors.
In the above visualisation, I found it hard to understand the deformation direction without the vectors, this is because the fluid under the surface isn’t always flowing in the same direction as the slosh making the deformation appear to be going in the wrong direction: