Hey everyone, I'm pretty new to DOP's but the current fluid solutions I'm using aren't cutting it. I decided to take apart the smoke solver otl to see how it was working and I had a few questions about gas simulation in Houdini. What type of advection does the Gas Advect op use? I assume it's semi-lagrangian. Are there plans to add some other types? Would it be possible to have an HDK example uploaded to the exchange for people to have a start from for implementing their own?

In the Gas SubStep op there is a Primary Solver slider. What are the other solver types? Is it possible to add your own custom solvers or would one have to write a gas substep type node from the ground up? Does the Gas SubStep node require all the inputs? So if I didn't want any heat calculations done could I just not include it or would I need to create an Empty Data op and plug that in?

Also are there any plans to offload some of the dops stuff to the GPU? There are some really cool examples out there. In the GPU Gems 3 book they had another fluid solver that is reqally amazing. You can check it out here:
http://www.cs.caltech.edu/~keenan/project_fluid.html [cs.caltech.edu]
There's a lot of cool sample movies and a demo. You're going to need a pretty beefy graphics card to check it out. There's some problems with it but if you're simulating this fast it wouldn't be as big of a deal to massage some of the data after.

Smoke in a box
http://www.cs.caltech.edu/~keenan/video/djinnsmoke.avi [cs.caltech.edu]