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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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22 views

Motion of an object due to movement of ship

I wanted to know how the movement of the object floating near the boat would be like. I've assumed the following scenario: The floating object is at the location $(x, y)$. The boat starts moving from ...
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1answer
26 views

Valve/Filter allowing through gas only, no liquid

I need to devise a way to ensure only NG passes through a pipe, and no condensates or other liquids. It is ok to shut down the pipeline if liquids would be detected. The dimensions involved are small ...
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22 views

Would there be rush of water underwater if a building was filled to the brim with water?

I'm writing something and I'm curious about how underwater currents would work. Say a five story apartment building was submerged on the coast of a beach, and it was filling with water. If water ...
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1answer
17 views

Air flow bench connected with a manometer. Atmospheric pressure of the manometer changes each time the bench is restarted. Why?

I was doing the air flow in a 90 degree bend experiment. On the first run, I connected the manometer to the tappings on the outer wall, then I turned off the bench and changed the connections to the ...
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1answer
28 views

Can anyone explain calculation of net force due to pressure in a streamtube of fixed control volume and infinitesmal size

I am studying derivation of bernoulli equation from FM White's fluid mechanics and in that pressure distribution is as shown in the image 1. I am unable to understand force calculation as shown in ...
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26 views

Can Flowmaster be used to model an entire pipe run?

I just started using the Flowmaster program (ver 08.11.01.03 if relevant) to model a series of stormwater pipes which are almost certainly in a pressure flow situation based on a first round analysis ...
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1answer
14 views

Lift and drag force measurement in a flume

I'm trying a test a hydrofoil in a low Reynolds flume, but struggling to find a way to mount the hydrofoil in the flume and measure the lift and drag force. I have some idea of using a load cell but ...
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20 views

Translation of vibrational motion in the 15-20 Hz range

Is anyone familiar with how to create a "shaking" fluidized bed. With vibrational amplitude in the 2" range and Hz 15-20? I'm constructing a vibrational fluidized bed dryer for the purpose of drying ...
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1answer
51 views

Question About Pumps in Series

I have a circulation tank that runs a piping loop out and back in with a motor pump on it to keep fluid constantly agitated in it. I want to add an inlet to the tank, so I can fill it without pouring ...
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15 views

How to calculate flow coefficient to choose a pressure regulator

I'm attempting to choose a pressure regulator(for use with an inert gas) for a personal project I am working on. I know that the inlet pressure will be 2000 psi and outlet pressure of 300 psi. I also ...
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32 views

How to derive a value from a transfer function

I have a scenario where a valve q_in(t) is pumping water into a tank of height h(t) and area A, which is then pumped out by a second valve q_out(t) that has a resistance to water flow R. I got this ...
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12 views

How to model the thickness of a liquid film between two flat surfaces?

Say there is a flat surface with a liquid drop in static equilibrium exposed to the atmosphere. Another flat surface [eg:glass surface] is place on top of the liquid drop and pressed down with an ...
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3answers
41 views

Hydraulic linear actuators as CNC axis instead of screws

Lately I've been watching some videos on machining and hydraulics as it always interested me. I was toying with the idea of building a budget CNC mill with threaded rod for the axes, but the issue of ...
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1answer
27 views

How is the Outlet flow rate in a water system controlled?

The Hardy Cross method for analysis of fluid systems assumes that in inlet flows and outlet flows for the system are known. However, when one constructs such a system in real life, how do we ensure ...
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13 views

Reformulate navier-stokes in terms of perturbation

I am reading this paper and trying to understand on page 14-15, First it rewrites Navier-Stokes in terms of a ''zero order problem'', and where $u_i = \mathscr{U}_i + u_i'$ , where $U_i$ is the base ...
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17 views

Flow through an Annular Orifice for Pintle Injector

Our rocket team is trying to finalize the design of our injector for a small liquid rocket engine. The current analysis challenge is verifying the correct pressure drop across the annular orifice ...
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0answers
34 views

Conceiving a wind turbine as a thermodynamic machine

Traditionally, and continuing till the present day, wind turbines are conceived/presented as power plants which harvest the (macroscopic) kinetic energy carried by an externally available airflow, ...
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10 views

Process control on reagent addition system

It's been a while since my fluid mechanics/process control courses at university. Due to my new role I have to dig up the old material again and start refreshing my brain! There is one scenario ...
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0answers
15 views

Reality check: Sub-sonic convergent nozzle for raising gas velocity to achieve required velocity head

The situation is as follows: atmospheric air is accelerated to 5 m/s with an idealized disk actuator, then passed into a convergent nozzle such that it's velocity is raised to 339 m/s and then flows ...
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1answer
26 views

Boundary Layer Thickness for Flat Plate

I did a Civil Engineering course some years ago and from my textbook I had a question on boundary layer thickness. So far I have been able to calculate the transition distance, but I am not sure how ...
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0answers
33 views

Finding Horizontal and Vertical Force on Bending Pipe

I did a Civil Engineering course some years ago and from my textbook I had a question on a bending pipe. The purpose of this question is to see if the way that I have calculated this is correct, as ...
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2answers
71 views

Find Torque and Force on Pipe with Bend

I did a Civil Engineering course some years ago and from my textbook I had a question on a pipe with a bend. Now I think I have the part of the question on force correct, but I am not sure how the ...
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1answer
26 views

Low-Flow Nozzles for Corrosion Spray Testing

So, for a cyclic corrosion test system, I need a nozzle or arrangement of nozzles that provides a flow rate of 45ml-140ml of salt solution per hour to an area 60cm square. All commercial nozzles I've ...
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1answer
29 views

Valve that opens at low pressure closes high pressure

My fluid handling system requires a valve that will open at low pressures (2-6 PSI) and close at high pressures (8 PSI). Is there any commercially available valve that is suitable for this application?...
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1answer
27 views

Liquid delivery to a pump based on viscosity

I have a tank that is filled with a viscous liquid (~3000 CPs). At the bottom of the tank there is a pipe that leads to a gear pump. There is 22" of pipe straight down from the tank followed by a ...
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0answers
88 views

Calculate Power for pump

I did a Civil Engineering course some years ago and from my textbook I had a question on a pump with hoses. Unfortunately I haven't been able to find a solution to this yet. A pump feeds two hoses, ...
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0answers
23 views

Force exerted by a jet of water on a series of Radial Curved Vanes

Normally, when we calculate the force exerted by jet on vanes, we usually calculate the rate of change of momentum. The momentum change is calculated using the relative velocity of jet with respect to ...
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1answer
28 views

O-Ring Design for low pressure applications

I'm trying to figure out how to create a seal for a very low pressure gravity feed system. Essentially its a low pressure solenoid valve. Is there any equations to estimate the amount of force you ...
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0answers
32 views

Equation to calculate flow rate

Assume you have a solid walled sphere with an opening of diameter x. The sphere has volume 0.02 litres and has air at 1.4 bars. What general equation would be appropriate to correctly size the ...
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10 views

Minor losses in a header

I need to calculate the minor losses in a steam header. I have calculated the major friction losses. But I can't figure out how to find the minor losses since the header has multiple tappings and not ...
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1answer
32 views

What is the effect of different ways to adding liquid materials into a mixing tank?

I am working with body wash products and there is a problem happening with the mixing process. I use a 5000-liter tank to mix all the liquid materials including water, surfactant and preservatives. ...
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2answers
107 views

From a mechanical point of view(Physics/Engineering) why are Front-Load washers said to clean/wash better than Top-Load washers on average?

Which cleans better? Is it just marketing or do they really clean/wash better due to some physical property or the way they work, I am asking how do they if they do? N.B I do not intend to indicate ...
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0answers
14 views

Comparing power requirements of centrifugal pump installations

Hi, I am stuck with a question related to the centrifugal pumps. There are two centrifugal pump installations and it is asked to compare the power requirements for two installations. As in Pa>Pb or ...
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18 views

Is it possible to reduce energy consumption of air separation unit by using single column rectification process?

Is it possible to reduce energy (Joule or KW) consumption of air separation unit by using single column rectification process instead of double column rectification? Is there any examples that this ...
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38 views

Most efficient turbine for harnessing energy from bidirectional air flow?

I am currently working on designing an oscillating water column as part of a project. In summary: OWC are devices with a semi-submerged chamber or hollow open to the sea below, keeping a trapped ...
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1answer
21 views

Can a “surface drive” propeller be submerged if induced supercavitation reduces water surface area?

Assuming induced supercavitation (like Supercavitating torpedo and Juliet Marine Systems Ghost) reduces water surface area does that reduce friction enough to submerge a surface drive propeller ...
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18 views

Submerged gate hydrostatics question

I know I must integrate this problem, but I am confused as to what exactly I supposed to integrate. Could you help me with the method for solving this problem? dF = rho * g * y
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1answer
44 views

Calculating mass flow rate of a scramjet engine?

First post here. I'm an undergraduate ME interested in fluid mechanics. I came across scramjets and I was interested about the engine. I want to calculate the mass flow rate of the engine and I made ...
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1answer
27 views

Pressure Coefficient with a Minima of 0 on Compressor Airfoils in Cascade

I am a relatively recent BSME graduate working on reproducing the results of a technical paper to strengthen my ANSYS CFX skills. The paper is "Effect of Section Thickness and Trailing Edge Radius on ...
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1answer
30 views

How to infer from the volume fraction function whether a flow is transient or steady?

Hello dear engineering community. I have a specific question about multiphase flows. I was wondering if anybody could help me with it, please. Assume, I have a one dimensional water-air flow. Air is ...
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1answer
33 views

How to calculate the viscous damping coefficient given drag force

Force due to drag at low velocities, is equal to some constant times negative velocity $$F_{d}=-c_{1}V$$ The viscous damping coefficient equals decay constant divided by 2 times mass $$\gamma = \...
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1answer
34 views

What Is The Liquid Depth Inside The Tank?

I know that $P_{total}=P_{gauge}+P_{atmosphere}$, so $P_{gauge}=P_{atmosphere}-P_{total}$ $P_{atmosphere}=101.325 KPa$ and $P_{gauge}=0.2 psig=1.38 KPa$. $P_{gauge}=(0.8 \times sin{30})(900)(9.807) -...
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17 views

Question with regard to spacex raptor engineand other full flow staged combustion engines

The diagram linked is unofficial but I've looked at other diagrams which are similar. The coolant is pumped in at a high pressure much higher than the maximum chamber pressure of the rocket the ...
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1answer
43 views

Fluid Mechanics - Fluid flow

I have answered the following questions, however I’m unsure if they’re correct. 1.) For this question do we consider gravity force, I have used it but I’m not sure if this invalidates my overal ...
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0answers
13 views

Efficiency of pump on VFD?

If I'm replacing a control valve with a VFD for a centrifugal pump, how do I predict the pump efficiency? I've got a pump curve which tells me my pump's efficiency at at a given flow or a given dP ...
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0answers
37 views

Grad student needing help with a fluid mechanics issue in project

BROUGHT OVER FROM PHYSICS STACK EXCHANGE As the subject states I have hit a wall in a fluid mechanics associated problem in designing an experiment for my grad project. Long story short, I'm an ...
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1answer
40 views

Does turbulent river flow classify as uniform?

I found this meme in a facebook group on engineering concepts: I selected A (steady and uniform). In selecting A I assumed the width of the river to remain constant along its path and no parameters ...
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0answers
10 views

What version of ANSYS is useful for simulation flow in a fin heat sink?

I'm interested in learning flow simulation in ANSYS and have found several tutorials. However, none say which version of ANSYS to download. The options are "Discovery Live Student", "Discovery AIM ...
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1answer
75 views

Could boiling water inside a semi-enclosed pipe be a low-cost method for a silent marine propulsion system? (redesigned)

I am wondering if boiling water that is trapped inside of a semi-enclosed pipe would be a low-cost method of creating an underwater thruster that would function as a silent marine propulsion system. ...
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1answer
35 views

Laminar flow hood/air straightener

I was looking at laminar flow filters to aid in my mycology work I'm doing. Most filters use an aluminum extrusion with fins. I figured the options out there are pretty expensive for what you get and ...