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# Questions tagged [flow]

The motion of fluids (gases, liquids and granular material).

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### Calculating the required amount of compressed air in order to achieve a desired flow rate (liquid) out of a tank [on hold]

I am working on a system that requires using compressed air to push a liquid out of a tank and through a nozzle at a constant flow rate. My question is how do I calculate how much pressurised air I ...
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### Fluid Mechanics (compressible flow question) [on hold]

I am a grader for a fluid mechanics class, and have come across a problem that I don't understand the answer to, and I was hoping someone could explain it to me. I've quoted the question below. ...
32 views

### How do I calculate fluid velocity in an open channel?

I'm doing an experiment on hydraulic jumps I know my flowrate, however, I need to calculate the fluid velocity in m/s in order to be able to plug it into the equation for hydraulic jump headloss. I'...
26 views

### Fluid flow between two reservoirs [closed]

I recently encountered a question related to Bernoulli equation which left me very confused about the basic physics here. Say two reservoirs are conncected via a pipe and I want to know the flow ...
32 views

### Joukowski airfoil [closed]

how do I draw Joukowski airfoil through its points, in the SolidWork app? like this: https://en.wikipedia.org/wiki/Joukowsky_transform#/media/File:Joukowsky_transform.svg
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### What's the link between Eulerian/Lagrangian approaches and macroscopic/microscopic point of view?

From what I know, in fluid dynamics, the Eulerian approach studies points that are fixed in space and time, while the Lagrangian approach studies individual particles and follows them. Is it correct ...
92 views

### Relationship Between Differentiation in Two Frames

In section 10.3 of Principles of Ideal-Fluid Aerodynamics by Karamcheti, he writes the following: $\qquad$ Denote by $K_1$ a reference frame fixed with respect to the moving body. We shall denote ...
271 views

### Why does water fall sort of helically from a cup? [duplicate]

I noticed today that if I took a glass of water and poured it out slowly (small tilt to the cup), it flowed rather smoothly, but when I increased the tilt the water flowed in a sort of helical manner, ...
29 views

### Limitation of continuity equation

Why continuity equation is not used in deriving/ finding the velocity for pitot tube where as both Continuity and Bernoulli's equation is used for deriving/ finding the velocity at throat in ...
23 views

### Gas Flow Rate and Pressure Difference

I have a pipe with two ends and on each end the pressure of the air is different. Is there any relation that can tell me the flow rate/speed of air inside the pipe because of the difference in ...
11 views

### Effect of Force(ex:Ship movement) on objects(nodes) deployed in the sea or ocean

I am looking for a mathematical model describing the motion of nodes deployed in sea due to movement of ship(a Force) or due to water current. I came across the drag equation which is used to ...
18 views

### Is it possible to equate the radius of a hole using poiseuille's law?

I want to calculate the radius of a hole from the leak rate. I have come across Poiseuille's law which includes the radius of pipe/hole. Is it possible to equate the radius of the hole from the volume ...
41 views

### Is Coefficient of viscosity frame dependent? Why/Why not?

Is Coefficient of viscosity frame dependent? Why/Why not?
59 views

### What are good textbooks or documents to learn numerical simulation about open channel flow like river flow?

I'm trying to learn about numerical simulation about river flow. The problem is I am a CFD beginner (just studied about hydraulics). So I don't know history or important topics about numerical ...
77 views

### Why is the stress tensor simplifying like this

\begin{eqnarray} \nabla \cdot \boldsymbol \tau &=& 2 \mu \nabla \cdot \boldsymbol \varepsilon\\ &=& \mu \nabla \cdot \left( \nabla\mathbf{u} + (\nabla\mathbf{u}) ^\mathrm{T} \right)\\ &...
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### Maximum velocity of isentropic compression

In the isentropic compression tables, if P/Po = 0.9999, then A/A* = 57.8738. This is from the isentropic compression table found here: http://www.cchem.berkeley.edu/cbe150a/isentropic_flow.pdf Am I ...
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### Finding the flow rate of a gaseous oxidizer flowing through a solid fuel (and they're combusting!)

I'm wondering, is there a way to calculate the volumetric flow rate or mass flow rate of oxygen flowing through a solid fuel (ex. paraffin wax) and combusting with it? After the combustion, the flow ...
3k views

### Water Bottle Rocket Thrust - two calculation methods not matching

I have been launching water bottle rockets with my kids and we are in the process of creating a simulation of the launch using numerical methods. I am a mechanical engineer, but fluid dynamics is not ...
35 views

### Air velocity from a 5mm pipe

At first, I will try to describe my problem. I have a compressed air at 0.4 MPa (4 bars) that goes trough a control valve and a flow meter into two 5 mm pipes. Flow meter shows the value of 200 ...
26 views

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### Flow velocity ambiguity in transition region

I have calculated the following short table concerning the stationary flow of water in a 1 meter long pipe with a diameter of 16 mm and a completely smooth inner surface. The flow is driven by the ...
### $Gm/r$ in momentum equation of compressible flow for cylindrical geometry
In the case of compressible flow, due to the gravitational field, the source term added in the momentum equation (which is gravitational potential) is $Gm/r$ in the case of cylindrical geometry and \$...