What is the formula to determine the change in pressure when there is a change in flow?

[Updated to help clarify my question] I have a current water flow of 9 GPM (gallons per minute) at 50 PSI through a 1/2 inch diameter pipe pouring out at the end. I understand that if I reduce the flow at the end (exit) of the pipe, it will increase the pressure of the water … Read more

Why does Bernoulli’s principle work?

So, if we have a large pipe which is constricted in the middle, the fluid in the middle section will move faster. Why is it so? What dictates that liquid that an X amount of it must pass on the other side regardless of the size of the encasement? The only reason I could think … Read more

Concept behind Reynolds number

I would be glad if someone can explain to me the concepts and the applications of Reynolds number in real-life. My handout has this explanation and I cannot understand it clearly… Reynolds number denoted by NR is an experimentally deduced relationship which is used to determine whether the flow is laminar or turbulent in a … Read more

How fast do the aerodynamic forces on a surface build up?

I`m currently working on my thesis in the field of active car aerodynamics. In order to design a controller to move parts of the cars body I need to know how fast the drag and downforce acting on this surface build up. So far I have found out about the Wagner formula, which gives the … Read more

Hydrodynamic interaction between two spheres in Re≪1Re\ll 1 flow

I am studying the interaction between two spherical particles of radius a in a low Reynolds number flow. Because of linearity, I know that their respective velocities will be linear in the forces applied to them. Similarly, the force \boldsymbol{F}_j applied on one particle contributes to the velocity \boldsymbol{v}_i of the other through a term … Read more

Does laminar flow of a mixture tend to result in mass separation?

In a laminar flow regime, a fluid separates into streamlines with a parabolic flow profile. Do particles within such a flow tend to become aligned by mass (e.g. lighter molecules travelling together in faster streamlines)? Or are the flow characteristics of the individual particles basically mass-independent under laminar flow? Another way of asking this question … Read more

What’s the best way to orient the bathroom door to optimize fart fan efficiency?

When using a fart fan I often close the bathroom door to around a 10° angle. I have no real idea why except for this strange notion that limiting the fresh air intake might increase air pressure and somehow accelerate the stale air in the room up through the exhaust. Which clears the smell quickest: … Read more

Compressible fluid flow through a branched pipe junctions

Backdrop: Designing a dust extraction system (LEV) with a branched junction. What principles allow for the calculation of volume flow rate and pressure at the inlets if the volume flow rate and pressure is known at the outlet using a compressible fluid? I am familiar with Continuity and Bernoulli equations using incompressible fluids but clearly … Read more

What is atmospheric stratification?

In the context of atmospheric stability, what are the meanings of stable or unstable stratification? What is stratification? Answer Stratification is density variations causing the fluids to separate to different layers. As shown in the YouTube video “Stratified Flow -lecture”: AttributionSource : Link , Question Author : Maria Q , Answer Author : Nat

Air flow coming out of a fan feels much stronger than air flow coming in. Why? [duplicate]

This question already has answers here: Closed 9 years ago. Possible Duplicate: Why is exhaling more forceful than inhaling? If I put my hand behind my computer’s system block, I can feel a very strong flux of air coming out, as it is being pushed by the fans. However, if I put my hand in … Read more