One used example is a rover on the Venus because fluidics would keep working at the high temperatures.
I really wonder, how one would implement cameras, radar, or lidar for navigation and the radio uplink for remote control without using electronics.
Two other apps for fluidics from the old days were nuclear reactors which are full of hyper-purified water and implantables in the body like maybe your internal insulin pump in the year 2050 would have an insulin dosing program written in fluid mechanics of blood powered by blood pressure.
If we could just find a problem for the fluidics solution... Kinda like lasers in 1960, it works so now what do we do with it?
The other interesting fluidics note is its been popular in hard sci fi for decades (well, for certain very small values of popular). The problem with fluidics is you need a pretty big digital computer to optimize the fluid mechanics and fancy digital computers to run the CNC machines to carve out the 3-d shapes. But if you could be VERY patient to do the calculations by hand and find a way to make the processors using 2-d photolithography maybe space aliens would have a fluidic technology.
Another interesting note is this scales by size and speed of sound in liquid so its always going to be slower than photonics or electronics. But, the computational power to do "stuff" seems to scale on a power law so the invisible hand of cheapness means your smart thermostat for a hydronic hot water heating system would inevitably be fluidic in nature given an infinite number of years of market pressure. Yeah, a "big easy to mess with by hand" system is as slow as a pocket calculator, but we sold the world a heck of a lot of pocket calculators over the decades and if you shrink the dimensions by a million and increase pressure modestly and you could run a fluidic cell phone, perhaps.
Sonar could probably be implemented using fluidics for navigation on Venus. Now a big problem is that it has traditionally been difficult to make fluidics operate at ultrasonic frequencies. There have been fluidic ultrasonic beam break sensors that worked on the principle of ultrasound disrupting a laminar jet to turbulence, but these can't 'directly' sense ultrasound. The response rate is also somewhat slow and not that sensitive. There are also means of heterodyning ultrasonic frequencies, but the method relies on a transitional jet so it's not reliable.
However, if you do the math it appears that fluidic amplifiers with dimensions that do not require semiconductor processing to make using a working fluid of helium should have flat gain to about 26 KHz, which is in the ultrasonic range. What really makes this work is the fact that helium becomes less viscous as it gets much hotter.
In fact power requirements for fluidic amplifiers may be about the same as their electronic counterparts(~0.2 mW per amplifier). In addition, laminar fluidic amplifiers have very low internal noise, meaning we should be able to amplify the fairly weak sonar return signals. A simple sonar sensor which reports back range should be possible, but a more interesting possibility is using acoustic metamaterials to do 'image recognition' to steer the rover away from obstacles.
A couple problems are how to couple sound from the fluidic circuits to Venus' atmosphere and keeping the helium contained. Having the entire circuit encased in metal and using metal would ensure that the leakage rate is insignificant. The issue is that making a reliable metal bellows pump could end up being a boondoggle. NASA tried to make an RTG that used a stirling engine rather than a Seebeck generator, but it stopped working reliably within a month or so, which may have been due to fatigue in the metal bellows. Another is it's difficult to determine sonar system performance due to the difficulty of calculating return strength
You would use magnetic logic. There are materials that can function as core memory, even at the temperatures of the surface, what is little known is that cores can also serve as logic units (NOR, NAND, etc) if they are given a suitable clock drive. This clock signal could be generated with an alternator driven by the wind on the surface.
