Hello everyone,
I have a question about drag force and pressure gradient force. The drag force occurs whenever there is a relative velocity between a fluid and an object. This force has a pressure component and a friction component. Now, what is the difference between the pressure component of the drag force and the pressure gradient force? Apparently it is not the same, because in the momentum balance the resistance force and the pressure gradient force appear separately. Could someone explain what exactly the pressure gradient force is? It is proportional to the pressure gradient and acts from the area of high pressure to the area of low pressure. But isn’t this also included in the drag force?
With best regards and many thanks in advance
Fritzi