Hi, I have a working fluid sim setup in H17.5 which, when run in H18, is totally unstable and immediately explodes. I now discovered exactly the same behaviour with another older project, which was done in H17 and shows the same explosive behaviour in H17.5. Both projects work fine in the original versions they were created in. So, not too much of a problem here. I would just like to know if this normal. Has anyone else come across something similar to this?

Cheers, Peter

Houdini is like that, it is a constant revision of the way it used to work. What you are learning now will probably be replaced in a year or two. It's part of the uphill battle to learn Houdini, it's always changing.

I'm realising that now.

It'd help if you can identify what's causing it and then report BUG

Houdini has always been good with backward compatibility, if there is a change to a solver or sourcing workflow or anything, opening old scene should still use old versions of the nodes and behave like before or at least work or require minimal maintenance to make it work

That being said there are occasional changes that may be backward incompatible, there can be also some bugs introduced that may break some deprecated workflows

So in any case it's always good to hunt down the reason to know for sure what exactly happened

Thanks! It seems to be related to surface tension. Both setups have it set on and when switched off things calm down.

For now I'll just carry on in the version they were created in. No big deal.

In that case it's probably this
https://www.sidefx.com/forum/topic/71904/ [www.sidefx.com]

Which was a fix to surface tension to be independent of resolution

It's one of those minimal maintenance cases I mentioned

Chances are that you'd have to adjust surface tension in previous versions every time you change particle separation to get comparable result
So take this as one last adjustment, but the benefit is it'll be resolution independent from now on

Ok, that makes sense. Thanks.