The second sim is a gas explosion. I want the explosion to expand fast in first few frames and then keep rising to form a good shape. The emission should be pretty hard at first and disappear slowly.
I firstly made a rough sim to test parameters and the range of explosion. The first test has a lot of problems: bad shapes and bad emission, the speed of buoyancy is not satisfied enough.
After that I adjust the sim to get a better result. I also add a shockwave to make the ground sim more interesting and interactive.
I then build a scene and an animated camera to fit with the explosion. At first I tried to render it with arnold. However, it takes about 20min to finish one frame, which is way slower than I expected. Therefore, I turned to render it with redshift, which is a faster GPU render engine.
The volume shader in redshift is not as good as the one in arnold, which took me a lot of time to finish the shading. After rendering, I composited it in Nuke, adding vignette and grains on the shot.
Below is the compositing breakdown:
Zhenzhong told me that the color of the explosion may have some problem. I also think that the color of flame is too bright. I will test this short again to make it looks better.