> ... the requirements in computer graphics are more inclined towards making something that looks right instead of getting the physics right.
That is exactly correct. That said, as something of a physics nerd (it was a big part of the EE curriculum in school) people often chuckled at me in the arcade pointing out things which were violating various principles of physics :-). And one of the fun things was listening to a translated interview with the physicist who worked on Mario World at Nintendo who stressed that while the physics of Mario's world were not the same as "real" physics, they were consistent and had rules just like real physics did, and how that was important for players to understand what they could and could not do in the game (and how they might solve a puzzle in the game).
Yes, consistency. Similar in scifi/fantasy, where an absurd conceit is believable if internally consistent, i.e. self-consistent. (I also call it principled) Too much ad hoc prevents suspension of disbelief.
Reactions are an important part of this, it's not just how good an actor is, but how other character react to them. If they are ignored, it's like that character doesn't exist, has no effect, is inconsequential, doesn't matter... is not real.
In a fluid simulation, when water does not react to the shoreline, rocks in the water, columns supporting a pier etc, it is like the water (or the obstacles) don't exist. In this sense, the water (or the obstacles) "aren't real".
For example, the water in Sea of Thieves looks magnificent... but because it doesn't interact (it's procedural), it doesn't feel real. It isn't real.
A further problem here with water is that it's difficult to make a continuous fluid that is consistent and isn't realistic, because the basic principles of fluid are so very very simple: conservation of mass, conservation of momentum.
[ Of course, you can still vary density, gravity. There are other effects beyond these: viscosity, surface tension. Also, compressible fluids, different reynolds numbers, adiabatic effects, behaviour at non-everyday temperatures, pressures, scales, velocities, accelerations etc. ]
There are also simplifications, like depth-averaging (Shallow Water Equations aka St Venant), but again, it's hard to vary it and yet remain self-consistent.
Cellular methods - similar to conway's game of life but for fluid - maybe are an exception, because thet are self-consistent - but pretty far from "water", because not lack momentum (and aren't continuous).
The final issue is error: simulations are never perfectly self-consistent anyway, because they must discretize the continuous, which introduces error. In engineering, you can reduce this error with a finer grid, until it too small to matter for your specific application. For computer graphics, it only needs to be perceivably" self-consistent - and perhaps pixel size is one measure of this, for the appearance* of consistency, in area/volume, acceleration, velocity, displacement (...though, we can perceive sub-pixel displacement, e.g. an aliased line.)
An imperceptible inconsistency can become perceptible if it is cumulative, such as mass not being conserved very slightly, but over time the amount of water changes significantly - one ad hoc solution is to redistribute the missing water (or remove surplus) everywhere, to compensate.
That is exactly correct. That said, as something of a physics nerd (it was a big part of the EE curriculum in school) people often chuckled at me in the arcade pointing out things which were violating various principles of physics :-). And one of the fun things was listening to a translated interview with the physicist who worked on Mario World at Nintendo who stressed that while the physics of Mario's world were not the same as "real" physics, they were consistent and had rules just like real physics did, and how that was important for players to understand what they could and could not do in the game (and how they might solve a puzzle in the game).