How to measure a force in flow simulation ?

Hello,
I'm trying to learn how to use flow simulation. I have an object and want to know the strength of air resistance (the force applied by the air on the whole object). I launched a new project by applying an air flow of 30 m/s on the Z axis. Then I set as goal : GG Force (Z). I then opened the curve of the result and I get the force (Z) versus iterations. However, I don't understand the results. I would like the overall force exerted on the entire object. Is this is the right method to get the result I want?

Thanks