how to adjust trim tank?
 

0.20 adds 3 dials. I know the left dial represents trim tank,but what about the other 2 dials?

The right 2 dials comprise the depth over keel. The most right one is showing the finer digits. Similarly to the inside dial of the gyrocompass and bearing and gyro-angle on the TDC. There is a slight difference with the 25m depth dial though. The later seems shallower by 0.4 meters.

Thank u, pisces. But, as i know,the trim tanks system consists of 2 pairs of tanks ,one of which is located at the forward and the other pair is located at the aft.
These tanks are interconnected by pipes called trim lines, and the fluid used is called trim water. Trim water is circulated among the forward and aft depending on the required trim condition. Circulation is carried out either by pumps or by low pressure air.

So what the most left dial in wolfpack represent? The forward pair or the aft pair?Where is the lever or switch to active the pumps carrying out circulation?

It may have been so in the real type 7 uboat. But in the game it is simplified to 1 tank, and no apparent effect to stability (shift of Center of gravity). It just makes you heavier. And the forward dial shows how much is in the tank. You fill it or empty it with the 2 crank-wheels. That is it (at the current state of affairs).

As you can read the Wolfpack product description on the Steam product page, it was not meant to be an uber-realistic type-7 submarine simulator. It tries to find a balance with functional richness and operational simplicity.

I regret to hear that. In my opinion, an exact copy of trim tank system in real life would be a new milestone in subsim, resulting from new intricate physics mechanism introduced,which is vital in driving a real submarine.Actually, due to this mechanism and other factors, excluding spaceships, submarines are probably the most complicated vessels to drive in the earth.
Therefore, a precise simulation of trim tank system probably makes players distinguish seasoned skippers from rookies, who could adjust trim tanks uncorrectly, resulting in unexpected consequences, which are lethal in battle.
So I wish the devs could make the trim tank system more authentic.

Trim tanks would be great! This would mean attention needs to be paid to the trim angle of the boat as well as the overall buoyancy when adding or removing trim water.

The current trim tank is great, but a bit too simple.

It would be great also if the boat accounted for whether fore or aft torpedoes were fired, so we'd have to not only correct the buoyancy but the trim as well.

Even if the system is still simplified, two trim tanks (one fore, one aft) would suffice.