# Questions tagged [fluid-mechanics]

Questions relating to fluids at rest (fluid statics) or the forces and effects of fluids in motion (fluid dynamics).

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### Confusion between Steady flow and Space-Time invariant density field

Let's take the example of a steady flow with velocity field as $u=βr(\tilde{r})$. Now, we can find a density field $ρ(r,t)$ that satisfies the mass conservation equation of $∂ρ/∂t+∇(ρu)=0$. First, ...
1answer
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### Pre requisites for a course in Heat Transfer from Fluid Mechanics , for a Mechanical Engineering Bachelors Degree [closed]

Can anyone please tell me the topics I need to study from Fluid Mechanics, specially fluid dynamics to understand Heat Transfer in a better way?
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### What is a safe and efficient temperature range for absorption chiller generators?

I've read that the role generators play in the absorption chiller cycle is to concentrate the salt solution so that the evaporator/absorber can maintain a vacuum by constant absorption of vapour ...
1answer
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### How Do I Calculate the Velocity of the Flow That Is Sucked Into Two Parallel Walls by a Fast Moving Flow?

I'm trying to solve a problem where I calculate the velocity of the setup bellow. Basically I have two very long(basically infinite for calculation purposes) plates, and I have one central jet of gas ...
1answer
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### In which bucket , should the water fill it up first?

Here , we have two water filters and buckets . Now , we know that as the water falls down , it’s speed increases because of acceleration due to gravity. Let us say I started both the filters and once ...
1answer
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### Angular Velocity And Flow Rate Relationship Of Turbine

I was designing a turbine to be utilized in order to measure the flow rate of a river system. I can measure the angular velocity of the shaft by utilizing a magnet and hall sensor, however, in order ...
3answers
194 views

### Given flow rate of an orifice at one pressure, how do I calculate flow rate for a different pressure?

Given an orifice rated 1.8 GPM of water at 90 PSI, how do I calculate the flow rate at 30 PSI and what rating I would need to purchase to achieve 1.8 GPM at 30 PSI? Below added to give some context, ...
0answers
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### Stokes Number (characteristic length)

I am working with a high speed flow that is non-stokesian, but that isn't the issue. There are correction factors for that. I am attempting to figure out what value to use for the "characteristic ...
1answer
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### Do throttling devices need valves?

Why is it that a throttling device always has a valve leading to it? If in a closed system loop, a cooled gas exists right before the throttling device, shouldn't the sudden decrease in cross-...
1answer
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### How does steam in almost vacuum condense at 35 Celsius?

I read about absorption chillers and found out that the water is evaporated/boiled off at the generator. Water boils over at about 3.7 Celsius in the near-vacuum conditions in the generator. Now the ...
1answer
41 views

### Absorption chillers: can they achieve temperatures below zero Celsius?

If I understand correctly (history shows I probably don't), then the only reason why the absorption chiller evaporators are restricted (I hope that's the right word) to extract just enough heat so the ...
1answer
46 views

### Which kind of paper has highest absorption speed?

I am experimenting to analyse the liquid wicking(radial) behaviour of various liquids. I have performed initial studies and experiments on household paper towels but they tend to deform and stick to ...
2answers
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### What are the benefits of reducing valve duration in an engine?

From my understanding this would be beneficial if you've taken a stock engine and put a smaller, more restrictive air intake on it. It would also be done to create more low end torque which shifts the ...
0answers
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### Will high velocity air directed underneath a half-toroid shaped Coanda saucer by a centrifugal impeller create a lifting force?

I would like to know if a lifting force will be created by the Coanda effect from high velocity air that is directed underneath a half-toroid shaped saucer by a centrifugal impeller. I am seeking an ...
0answers
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### Symbol for background shear

Can someone please help me with the symbol for background shear? To give you a bit of context, I am referring to background shear as in the following sentence taken from Hussian et al.: Vorticity ...
1answer
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### Component selection type for fluid-mechanical system

I am creating an enclosure and need to get a water supply through a plastic wall inside to the core device. I imagine this water line will be a flexible tube and will screw on or snap to an adapter on ...
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### Imposing/ensuring a constant mass flow rate in turbulent flow simulation

I'm trying to simulate using Finite Elements (non commercial software) the Tube Bundle benchmark problem: http://cfd.mace.manchester.ac.uk/ercoftac/doku.php?id=cases:case078&s[]=tube&s[]=...
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### Selecting a water pump for low flow and 1 Bar pressure

I am designing a small automatic drip irrigation system. There will be about 10-15 drippers. Flow through the system will be about 1 l/minute, but this may change if expanding or reducing the system. ...
0answers
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### Fluid dynamics through tee wye bend

I'm designing a small system where typically a ball valve is used to divert water through a heater when desired. I've noticed the ball valves designed for this situation result in a hard 90 degree ...
2answers
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### How to use excel spreadsheet formulas to find optimal camshaft profile [closed]

I have a 600cc 4 cylinder Honda engine that my race car team uses. The rules of the race mandate that we install an intake that is substantially smaller than the stock factory intake size to limit ...
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### Why is it more convenient to express stress tensor in Material rather than Spatial coordinates?

I was reading chapter introduction about Stress and the author wrote the following about stress tensors: "Since the current configuration of many problems, especially those involving solids, is ...