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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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ANSYS Fluent - Using Patch to set initial conditions, should I set the pressure and velocity or only one property to generate shock waves in a pipe?

I am fairly new to CFD and I am working in ANSYS Fluent. I am trying to model two specific shock waves in opposite directions in a length pipe. The shock waves need to be traveling at specific Mach ...
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Can you help me with a flow rate question?

How many gallons of water (70 degrees F) can flow thru a pipe diameter (I.D. 0.475") at 50 psi over a 30 foot length in a 24 hour time frame?
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Extrapolating BHP values for fixed speed and impeller diameter

currently i have a composite pump curve (RIGHT) where the BHP lines are embeded in the performance curve. I would like to extract out the data and create a graph of BHP vs capacity shown on the LEFT. ...
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Modeling Friction-reduced Pressure Drop in Natural Gas Flowing along a Horizontal Cylindrical Trunkline (Pipe)

I am seeking some help related to part of a project I am currently working on, where I require to (data-driven) model the pressure drop due to friction for natural gas flowing along a horizontal ...
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1answer
28 views

Do pressure regulators restrict the mass flow rate?

Suppose we have a tank containing compressed air. If a hole is made in the tank the air will start flowing out. The mass flow rate of exiting air will be heavily dependent on the diameter of the ...
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1answer
29 views

what should be the size of gate? [closed]

what should be the size of gate? if street 8 ft according to house map Car entrance gate 11 ft can corolla grande car enter into the gate easily with some moves?
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1answer
38 views

How do I calculate the force coming from the centrifugal compressor exhaust?

Let's say I have a centrifugal compressor as shown in the figure and I know the following parameters----1 Thrust Inlet and outlet pressure Power required to operate the compressor Inlet and outlet ...
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3answers
28 views

need to know flow rate

I have 5/8" PEX piping (I.D. .475") throughout house. Am connected to city water supply (@ 40# psi) all new PEX pipe, all new valves....no leaks In April, 57,000 gallons reportedly flowed thru the ...
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How to get resistance K factor of order 10^4 with complete freedom to vary the geometry?

I want to design a tube (radius=2mm) with a K-factor (https://neutrium.net/fluid_flow/pressure-loss-from-fittings-excess-head-k-method/) of order 10^4. Could this be done by putting multiple orifice ...
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1answer
26 views

Soil mechanics-Geotechnical engineering [closed]

Which is more economical to improve or change the soil that is used to build a structure? my answer is that it depends on each case, but I would like to get more information, or where to search about ...
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Regarding the ITTC Guidelines for Ship CFD applications

I was reading through the ITTC – Recommended Procedures and Guidelines - Practical Guidelines for Ship CFD Applications (https://ittc.info/media/4196/75-03-02-03.pdf) document and this little thing ...
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Hydrostatics pressure forces

I can deduce the Forces for F1 and F2: $$\begin{align} F_1 &= \dfrac{1}{2}\rho g d_1^2 \\ &= \dfrac{1}{2} \cdot (1000 \cdot 9.81) \cdot d_1^2 \cdot 8 \\ \dfrac{F_1}{d_1^2} &= 39240\text{ ...
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Normal Stress Balance at Fluid-fluid Interface

I am trying to determine a normal stress balance at an axisymmetric and dynamic fluid-fluid interface, $z(r,t)$. For a static, free surface, this simplifies to the Young-Laplace equation: $$ \Delta p=\...
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2answers
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Why do (some) high-speed trains have curved (convex) walls?

Comparing the cross-section of modern high-speed trains to old train waggons, which had straight walls and were limited to speeds around 200 km/h, I notice that most of them have curved outer walls. ...
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Finding flow rate contribution from difference in temperature

Currently I am working on a DTS(Distributed Temperature Sensor)data and PLT data and I need to figure out a relationship between temperature and fluid flow-rates in various locations (depths) of the ...
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Simulating fluid dynamics for Generative Design of water turbine in Autodesk Fusion 360 [closed]

I am trying to use Autodesk Fusion 360's generative design feature to produce more efficient turbine blades for hydroelectric power generators. How can I simulate the load of water-fall on a turbine ...
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Method of Hydraulic Resistances (Crane TP 410), how accurate is it really?

A bit vague but a question for you working engineers out there. For a couple of years now I've been designing fluid systems, mostly using Crane's TP 410 as the guiding resource for pressure drop ...
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Buckingham Pi Theorem doesnt work for this case?

Question from my Fluid Dynamics book (White 7e - 5.15) The thrust F of a propeller is generally thought to be a function of its diameter D and angular velocity Ω, the forward speed V, and the density ...
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Why do we use tangential component of absolute velocity instead of relative velocity in Euler equation?

Power transfer in a turbomachine rotor is defined as: $$ P = T\omega = \dot{m}\omega(r_1C_{u,1} - r_2C_{u,2}) $$ Where $T$ and $\omega$ are the torque and rotational speed respectively, $\dot{m}$ is ...
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1answer
28 views

Static Head Assumptions

I have questions about a well pump application I am working on. It consists of a well that with a submersible pump that fills a reservoir tank. As far as I know, the tank is not pressurized. Here are ...
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1answer
19 views

How to obtain the $dC_d/dC_l^2$ value from the drag polar of an airfoil for Xrotor?

I'm currently trying to do an initial design for a propeller. In order to do this I'm trying to use Xrotor. Xrotor allows the user to enter certain information about both the propeller geometry, ...
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2answers
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Why doesn't axial turbomachinery blades block fluid from flowing?

I know this is a silly question, but shouldn't the high speed rotating blades (in case of an axial air compressor or an axial air fan for example) block the air from flowing? What makes air flow ...
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2answers
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Open Channel flow with pressure losses - flow depth?

In a horizontal channel that feeds off a river, does the head/pressure loss due to friction, turns etc in the channel translate to a drop in the water level between its inlet and outler? If so, could ...
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3answers
325 views

Will this water jet propulsion system design produce any forward thrust?

I am interested in building a very basic water jet propulsion system for a toy boat. Before I build it, I would like to know from a conceptual standpoint if this design of a water jet propulsion ...
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2answers
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Why boiling occurs when vapour pressure equals the local atmospheric pressure

When we increase the temperature of water in an open container, the vapour pressure increases.But boiling (phase transition at constant temperature and pressure) occurs only when the vapour pressure ...
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1answer
59 views

Will the airflow inside a vacuum hose keep a sphere centered inside of it?

Suppose you were to fasten a string to a ping pong ball, then fasten the string to a stationary object, and then use a vacuum cleaner with a strong vacuum to suck the ball partially into the vacuum ...
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Am I estimating thrust of a ducted fan correctly?

I'm asking if I'm doing this correctly. I've estimated the thrust of a ducted-fan model aircraft neglecting pressure changes across the duct as follows: $$F = Q * \rho * (V_e - V_0)$$ $$= Q * rho * (...
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2answers
57 views

Will circulating air within a sealed ductwork system cause it to implode?

Referring to the pasted in ductwork diagram, if an inline ventilation fan with a high CFM airflow was used to circulate air within a sealed ductwork system, would the fast moving airflow result in a ...
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Please help solve this problem! [closed]

Fluid with mdot = 0.025 kg/s and Tm,i = 25oC is flowing through a long metal cylindrical tube where the diameter is 0.032 m and the length is 2 m. The surface of the tube is heated with a heat flux of ...
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0answers
29 views

Designing a piston pump for windpump

I am designing a savonius type wind pump for low wind speeds(avg speed = 2.7 m/s), with these speeds and rotor area of about 2 m2. Acc. to my calculations, I am getting a volume flow rate of ...
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1answer
64 views

Steady Non steady and Uniform Non Uniform flow

Thanks in advance, can someone explain Steady,Non steady, Uniform and Non Uniform flow and provide some example for each.
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1answer
34 views

the angle of water surface in a moving car

in this picture, there is a container of water and it is moving on the slope. we want the acceleration of the container while the angle of water surface is parallel to the slope. so the book says the ...
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1answer
23 views

Minor loss due to splitting of pipe

I am solving pipe flow problems and it came to my mind how does one find out the minor loss associated with the splitting of pipe. Here how does one find the minor loss associated when the flow is in ...
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1answer
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Finding phase velocity for froude number scaling

So I am calculating phase velocity of a wave for Froude number scaling for model testing of a boat. I got data from Lloyd's Rules saying for the specific sea area I did $H_s=3.6\text{ m}$ and $T_z=6.8\...
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1answer
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Negative head in Darcy's flow equation

This question appeared in my midterms. A pipe transports water from a storage tank A to storage tank B. Storage tank A is at an elevation of 20 m above B, the pipe length is 6.4 km. The present ...
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Error analysis in venturimeter

A fluid having specific gravity $0.82$ and viscosity $1 \times 10^{-3}Ns/m^2$ flows through a $0.3m$ diameter line in a refinery.The flow rate is expected to be $140-180$ kg/s.The flow rate has to be ...
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How can pitot tubes give us local velocity in a flow

I am studying about static pressure,dynamic pressure and the principle behind pitot tube. However in pitot tubes we apply Bernoulli equation between two points which are not on the same streamline. ...
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Choosing a blower for a Pneumatic Conveyor

Basically we are designing a pneumatic conveyor system for transferring 11 tons of beans per hour. We need to decide on the specifications of the blower. What are the calculations necessary to decide ...
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1answer
25 views

How to use the moment-of-momentum equation for water flowing through a pipe?

I am having a lot trouble understanding this problem, I don't even know where to begin or how to articulate my difficulties, but I will try my best. Is the question asking to find the torque ...
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1answer
26 views

Optimal plumbing layout for 3 storey building?

I'm trying to design a plumbing system for a school project, and I want to verify that my initial piping layout from water source to outlets is logical before I start making calculations and programs ...
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1answer
38 views

Dimension Analysis For fluid mechanic

I have a question about the characteristic dimension. Q1 The drag on an airship is known to depend on the air density, ρ , dynamic viscosity, μ , speed relative to the air , V , and a characteristic ...
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3answers
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Curve Fitting Atmospheric Density

I'm trying to make some code to predict the performance of a sounding rocket I want to build. To do this, I need the atmospheric density at any point in the flight for the time-step simulation I made....
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1answer
32 views

How to use the linear momentum equation to determine the forces required to hold a nozzle stationary?

This is the problem I'm trying to solve: I'm looking at the worked-out solution from my professor and it shows that the sum of the forces in the x-direction is equal to: [d/dt(momentum) in the x-...
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1answer
45 views

Calculate hydraulic torque from motor HP, hydraulic pump and gearbox

I am curious about the design considerations for a hydraulic system. Let's say you have a 3HP 1200RPM motor you also have a hydraulic pump that's rated 4LPM and pressure of 40MPA rated for 40RPM MAX ...
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Liquid phase gas flow through valve

I have been trying to figure out how to calculate the required dimensions for liquid phase gas through a solenoid valve. Many companies (Swagelok, Bürkert, Asco) provide "Flow coefficient calculators" ...
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2answers
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Sea waves: Having trouble visualizing the difference between group celerity and celerity

What I know, if I'm not mistaken, is that group celerity is the speed at which the energy is transferred and celerity is the speed of the waves themselves. Since sea waves basically transfer energy ...
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3answers
149 views

How does an expansion tank work?

I know that a hydronic system forms a closed loop. When the boiler is turned on, the water temperature will increase and expand. Since this system forms a closed loop, there is no volume for the hot ...
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Where to put the booster pump at customer substation in a district heating system?

In a district heating system, one of the houses in the distribution net is not getting the desired heat into their house. This is because the pipes of this customer which connects them to the ...
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1answer
45 views

Which way should I build stairs into a creek?

I have a little creek in my back yard. It's slow moving and safe (as safe as a slow moving creek can be.) I'd like to build a little set of stone steps into the creek and am not sure of the best ...
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Time to empty a pressurize oxygen tank through a regulator

Time to empty a pressurize oxygen tank through a regulator. The tank contain 12oz of oxygene at 3000psi (room temp.) The regulator is set to 120psi. The exit pipe is a 14inch pipe with 2mm inner ...