Reaction force generated if a fluid flow changes direction and/or velocity.
The force F acts on the fluid from the outside as a supporting force. The force exercised by the flow on the environment is the flow force
![a671a14356836b559bacb196447a34788baf3b95 impulskraft_01.gif](/fileadmin/smc/files/a671a14356836b559bacb196447a34788baf3b95.gif)
The force F acts on the fluid from the outside as a supporting force (reaction force).
The force exercised by the flow on the environment is the flow force
This Bernoulli force can be seen, for example, with directional valves where, during opening, it exercises an opposing force on the valve control spool for which pressure is otherwise balanced (Figure I 4).
![64ec4ae5211788967e1bcd0d0662b96953f43d6c 0001_impulskraft](/fileadmin/smc/files/64ec4ae5211788967e1bcd0d0662b96953f43d6c.gif)
Figure I 4: Bernoulli forces on a valve control spool