Week 5 - Rayleigh Taylor Instability

https://youtu.be/Ys76Ii5aCiY for baseline simulation

https://youtu.be/lGWuQCzSSAM for 2nd case refined mesh starting from 0 time frame to 590 time frame

https://youtu.be/ybDBDjBK2Mo for 2 nd case refined mesh stars from 590 time frame

https://youtu.be/NqrQjEOIlfc for user defined function case 3

Calculation of Atwood number for 2 cases

First case Atwood number

Density of air = 1.225 kg/m3

Density of water = 997 kg/me

A = 0.997

For case 2 Atwood number

Density of water = 997 kg/m3

Density of lighter fluid = 400 kg/me

A = 0.4273

Conclusion

1. the comparison of different mesh elements for capturing the Rayleigh Taylor instability between water and air, the density of water is higher than the density of air, as this process states that difference in densities makes the lighter fluid moves upwards from bottom of vessel whereas the higher density fluid is pulled towards the bottom by gravity force due to heavier density, as the interface between the fluids is disturbed.
2. The finer mesh elements shows better results when compared to coarse mesh elements with just 3200 elements, but in case of finer mesh elements of around 32000 elements exchanging of fluids from bottom to top and top to bottom is shown very smoother.
3. Therefore finer is better in this simulation.
4. In other case the density of lighter fluid is changed to 400 kg/m3 and its dynamic viscosity to 0.001 kg/ms. In this approach the meshing elements have been kept at same number of cells and nodes, the simulation results shows that the mixing of fluids is slower as compare to air and water fluid due to less Atwood number which less density difference. This less density difference dampens the changing of fluids.
5. In case of two different cases the Atwood number showing in first a value of close to 1, which states that the mixing of two fluids will takes at faster rate, similarly in other case the value of Atwood number is below 0.5 which signifies that the rate of mixing or instability will more when compare to first. This change in rate is due to change in densities of materials.