According to Darcy's law, if you double the amount of coffee grounds in an Aeropress, and if you apply the same pressure, then the flow rate will

The flow rate will be unaffected when the amount of coffee grounds in an Aeropress  is doubled and the same pressure applied.

What is Henry Darcy's law?

Generally, Henry Darcy's law states that the flow rate of particles or substances between two defined points are directly proportional to the pressure difference that exists between them

Giving the equation

Q =kdP

In conclusion, if you double the amount of coffee grounds in an Aeropress and apply the same pressure,The flow rate will be unaffected.

For more information on Pressure

some think that theories become laws, but theories and laws have separate and distinct roles in the scientific method. a law is a description of an observed phenomenon in the natural world that hold true every time it is tested. it doesn't explain why something is true; it just states that it is true.

the part of the wave he is travelling on is the crest