Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [fluid-mechanics]

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

1
vote
1answer
21 views

Pressure rise in horizontal pipe

What causes the pressure change in a horizontal pipe with no energy input. Is it the head loss? If so, how?
0
votes
0answers
18 views

Flow rate for a domestic water flush

I have a 8" pipe tied into a 16" water main to be flushed. Specification requires a specific flow rate. Pressure is 85 Psi. and discharge is 4" and pipe is horizontal. Too much flow to normal ...
0
votes
2answers
44 views

What pressure to take in surface tension question?

Pressure inside a water droplet is $0.32 N/cm^2$ if surface tension of liquid is $0.095 N/m$. We have to find the radius of the bubble since it's a water droplet the formula used is $$P_i-P_o=\frac{...
2
votes
2answers
29 views

Force applied by fan under inviscid & incompressible flow

I have a wind tunnel (subsonic flow of air) which consists of a fan inside (and ahead of) a long cylinder of cross-sectional area of $A_e$, followed by a diffuser of $A_o$ c.s. area ($A_o>A_e$). ...
0
votes
1answer
56 views

Difference in Diameter calculation using Solidworks and manually

When I try to create a flat form of a archimedes screw using Solidworks it gives me a diameter different from what is calculated manually basically using a Pythagoras Theorem. Can anyone explain the ...
0
votes
1answer
23 views

Calculating typical floor fan efficiency or dP? (Spec sheet too good to be true?)

Looking to purchase a fan with high velocity. Trying to make solid data driven decision based on specs. Found that most fan's of the 20" diameter variety are around 3000 CFM; however found one that ...
0
votes
2answers
37 views

Polyurethane mix-on-the-spot system

3d printing is a slow process and for my solution I need fast printing. So I print with no infill and I fill inside with a two part, 10 min drying polyurethane resin. I mix them in a disposable cup ...
0
votes
0answers
29 views

Tempreture distribution in a furnace

I am simulating a furnace as follows: Is it possible to capture temperature distribution in this furnace without designing intake fan? Which kind of boundary conditions can replace with intake fan? ...
0
votes
0answers
24 views

Stream function in fluid mechanics

The stream function Ψ for a steady flow field can be defined as: ρU = $\nabla \times$ Ψ. Where, $U = velocity$, $ρ = density.$ Now, this Ψ can be in turn represented as: Ψ = χ $\nabla$ ψ. Where, ψ ...
0
votes
1answer
17 views

Torque on the curved moving vane

I was reading an article on the impact of jet in vanes. In this article I found that the net torque on the unsymmetrical or radially curved vanes is non zero. But, my question is that, why the torque ...
0
votes
2answers
50 views

Calculation for heat transfer rate / cooling capacity for air cooled solid

I have a pipe which is channeling air flow from a compressor with a known mass flow rate and temperature. I can adjust the mass flow rate (power setting) and measure the delta T for the temp of air ...
0
votes
0answers
10 views

How do I add multiple materials in Helyx-OS which use OpenFoam for CFD analysis?

I am trying to learn HELYX-OS which is a GUI for OpenFoam. But I cant seem to add more than one material for the system and it is only allowing me to add one material no matter which modal I use.
0
votes
2answers
32 views

What should be the density of a compressed gas while measuring the flow rate using Rotameter?

Say we have a required mass flow rate, in order to have equivalent volume flow rate, we need to consider density of the operating fluid (compressible fluid). To measure the volume flow rate in LPM, ...
0
votes
0answers
22 views

If I replace a flow orifice with a Coriolis flow meter of the same size do I need to worry about pressure drop with the new Coriolis meter?

I have a 3 inch line with a 1.5 inch flow orifice. If I take out the flow orifice and put in a 1.5 inch coriolis meter will the pressure drop be the same or better with the new coriolis meter than ...
0
votes
1answer
50 views

How to solve analytically this equation? [closed]

I need to solve the next equation and to find $x_1$: $$\dfrac{d(x_0x_1)}{dz}=-\beta\dfrac{dx_0}{dz}\dfrac{1}{r-z(r-1)}$$ where $x_0$, $x_1$, $z$ are variables, and $r$, $\beta$ are constants. At ...
0
votes
2answers
38 views

Why aren't turbos/turbines controllable pitch?

I am wondering why turbines are not implemented with controllable pitch blades (on the rotor system)? I assume the reason is that the coupling between the stator and rotor systems posed by typical ...
0
votes
1answer
31 views

Reduce and compute flow in self designed pen

I am currently designing a simple pen for drawing with different types of liquid varnishes. My current design has a tip at the bottom side of the pen (blue) and a tank at the top side where the ...
0
votes
2answers
41 views

How does placement of a pressure gauge in a tank of fluid affect the pressure readings?

This is not a real system but rather something I made up to understand how the placement of pressure gauge in a tank takes its readings. Here’s a diagram of it- The pressure gauge placed in the ...
1
vote
1answer
20 views

Why does the water pressure initially drop then stabilize when pressure testing a valve?

Sometimes the dropping goes on so long(10-15 minutes) that the test is thrown out and the valve is opened and filled with water for a longer period of time. Pressure testers claim that it is because ...
1
vote
3answers
40 views

Is there any entrance losses in this particular Pipe design?

Let’s say this odd design, the arrow is the direction of water flow (don’t ask why because I’m just curious about it)... I drew this out and just wanted to ask if water were to flow into the pipe ...
0
votes
1answer
42 views

Design of a small scale air curtain

I am new to the field, most of the papers I have searched directly conduct CFD simulation but skipped the calculation. I hope to get an estimation by calculations. I am designing a small scale ...
1
vote
0answers
22 views

Ansys Fluent: how to change the temperature digit precision in writing to file XY-plot?

I want to write to file data from XY-Plot with temperature depending on the location. In Axis menu I set a max precision (9) for X and Y. However, Fluent writes data like this ...
0
votes
4answers
84 views

what's the best shape for inducing condensation?

What would be the best ceiling shape for inducing condensation? I'm guessing it would a curve ︶ or V shape, but those are just guesses. (I don't have any background on thermal physics)
3
votes
2answers
81 views

Finding out torque in a viscosimeter

I am solving problems through Fox and McDonald.Here is the problem I tried by finding out the torque due to viscous forces which is $$\tau_1=\mu(2\pi Rh)\frac{R\omega}{a}$$ and the torque due to ...
1
vote
0answers
11 views

Does impeller design have a specific cause on how the fluid will flow in a centrifugal pump?

I am a student learning about centrifugal pumps in my studies. I’ve learnt about the 3 different type of flows - axial, radial and mixed. I’ve also learnt about different impeller designs - mainly ...
1
vote
1answer
44 views

How can i calculate drag on an Angled area?

I want to calculate drag force at special angle on a sphere . There are some grooves on the sphere and these groove have a special angle on the sphere. In other words, I want to calculate drag force ...
0
votes
2answers
68 views

Calculating piston mass, for transfering fluid through a length of pipe

I must clarify that I am not an engineer and I am not an engineering student. I am only doing a personal project in which I am stuck for months with the following problem, since my knowledge is not ...
1
vote
1answer
32 views

Easy model to calculate water flow rate over trough ledge?

Trough is 1.87 meters long and 0.5 meter wide and 0.22 meter deep. Water only flows over the 1.87 meter long side and from both sides (so x2). The water overflow is 0.012 meters tall (ruler ...
0
votes
1answer
29 views

Collision of submerged bodies

Let us assume that the an object collides into me in one of two scenarios, either I’m standing on shore, or else we’re submerged underwater. The object doesn’t change it shape, and possesses the same ...
1
vote
0answers
19 views

How to analytically estimate the pressure loss through an liquid injector?

The simple orifice and a pipe have well-documented pressure loss calculation. But when an injector has complicated flow patterns, is it possible to break it down into simpler sections by which the ...
1
vote
0answers
9 views

Shear between which two fluids is better for atomisation - liquid & liquid or gas & liquid?

In designing an atomizer which generates a spray of liquid, one can adopt atomisation through shear. Shear in the following cases are to be considered: stagnant Gas- moving Liquid: in this gas case ...
1
vote
0answers
16 views

Matching Output of Two Old Ring Compressors using Larger Single Unit

Disclaimer: I am new in the design of any fluid systems, however the selection of these units is critical for the electrical design I am responsible for this system, so please excuse me if my approach ...
0
votes
2answers
38 views

Will a fan that is composed of several fans fixed inside rotating tube work?

I want to design a custom 3D printed fan that would be made of several axial fans that would be connected (fixed) to their cylindrical casing. I am planning to rotate the whole assembly (the cylinder ...
0
votes
0answers
16 views

What is the relationship between coefficient of discharge, Cd and viscosity of the fluid?

Will an orifice’s coefficient of discharge depend on the viscosity of the fluid being used to measure it? During injector developments, we cannot afford to test with the intended liquid if they are ...
1
vote
2answers
32 views

Can I make check valve in simple workshop?

I need a check valve ( one way valve ) for my project which has less actuation force (IDK real term. shouldn't require high pressure for inflow of fluid) and I searched in market for the valve but ...
2
votes
0answers
21 views

The use of Theis equation based on time

The storage coefficient (s) for artesian basin can be determined by the following equation (Theis equation): $$s=\frac{Q}{4\pi T}\int_{\frac{r^2S}{4Tt}}^\infty\frac{e^{-u}}{u}du$$ Does this ...
1
vote
2answers
54 views

How does pressure drop occur across a pipe

Consider a pipe in which flow is taking place.A textbook says,when there is a valve or heat exchanger or resistance to flow between two points in this pipe,pressure decreases from one point to another....
1
vote
3answers
54 views

Will multiple lines off same water main have equal pressure?

I’m in a situation where a multi unit structure under construction will receive its water from local municipality via three metered 5/8” lines. We’d like to combine all of the lines into a 3” ...
0
votes
1answer
33 views

How to maintain a static negative pressure in a valve?

My target is to create a valve with multiple inlet capillaries. And my output is a pipe of a larger diameter. I do not want to use any electrical systems, and at the same time, I want to maintain ...
3
votes
1answer
72 views

Why do most centrifugal fans found in laptops have tiny blades?

If you were to use a centrifugal axial fan instead, won't you be able to achieve higher flow rates and better pressures? It seems like the efficiency of these motors are very low.
6
votes
0answers
58 views

Thrust distribution of engine

I am studying the thrust distribution of jet engines. But I'm now a bit confused. In Rolls-Royce's "The Jet Engine" book, http://aeromodelbasic.blogspot.com/2012/05/thrust-distribution-distribution-...
1
vote
0answers
20 views

Overcoming gravity with fluid pressure

How would I determine if an upward flow of liquid at 100 bar forces a bed of porous solid upwards or flows through without affecting the same bed of material? Is it related to bulk density and pores?
0
votes
2answers
45 views

Why do we need flow rate measurement devices?

When we can manually measure the discharge flow rate,what for have we developed the concept of venturi meter or orifice metre?
1
vote
0answers
17 views

Is RotCFD or Ansys Fluent better to capture the wake pattern far downstream of a flow in the case of a rotating blade?

My main constraint is that the wake pattern to be worked on is far downstream. Which one will give me more accurate results? Will these two work well for the far wake at all?
3
votes
0answers
36 views

Simplifying head loss across a piping network

I am tasked with designing a compressed air piping network,with and would like to determine the pressure loss across the different layers of instruments -now here is the 3D layout of the network. ...
3
votes
1answer
60 views

m3/hour of water at 12 bar through a 6" diameter open ended pipe 100 ft long

I have a water jet pump pushing water through a 6" diameter open ended pipe 100 ft long, I need to get 12 bar gauge pressure on the pump discharge, what size (m3/hour) pump do I need ?
5
votes
1answer
31 views

What is a 'swept path' in a valve system?

I have been doing some research on valve systems for sample analyzers. In many of the valve systems' product documentation they refer to a flow path as 'fully swept'. From the context I can conclude ...
0
votes
1answer
59 views

Pump power and fluid viscosity

I used to calculate the power needed by a pump using Bernoulli equation, $ W =(p_2-p_1) + {1 \over 2}\rho(u_2^2-u_1^2) + g\rho(h_2-h_1) + R $ where $\rho$ is fluid density (and assuming it is ...
1
vote
0answers
10 views

How can I mesure the axial induction factor of a small propeller using a DC motor?

I am trying to measure the axial induction factor of a small aeromodelling propeller. By axial induction factor I call the ratio of the velocity of the wind far from the propeller $V_{\infty}$ over ...
1
vote
0answers
37 views

Relation between airespeed and pushing force

I'd like to know how can I estimate the maximum speed that can be achieved by a "portion of wind" accelerated upward from rest on the surface of a place by pushing forces. So far I've thinking in the ...