What is Fluid dynamics: Definition and 630 Discussions
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.
Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and time.
Before the twentieth century, hydrodynamics was synonymous with fluid dynamics. This is still reflected in names of some fluid dynamics topics, like magnetohydrodynamics and hydrodynamic stability, both of which can also be applied to gases.
Let's say an object with a mass of 400,000 kg, a drag coefficient of C, and a reference area of A m^2 moves horizontally with a thrust of X N through a fluid with a density of Z kg/m^3. The object is initially stationary. I'm trying to figure out how I can express the drag force, acceleration...
My research is on radar images and the images are collected in several conical surfaces. These conical surfaces have the same origin, the same maximum length (max flare or max range), but different elevations angles. The images are collected on the surface of the cones only.
I want to determine...
Hi
The rotating bucket problem with a fluid is well known as a homework. For the fun i wanted to adapt it to the case of a massive non-rotating sphere surrounded by a fluid. However i don't know if the calculations i made are correct or don't make sense at all (even if the result lead to an...
TL;DR Summary: I am Highschool student writing a 4000 word research paper on Bernoulli's principle and the coanda effect. I need help with derivation of a formula that connects flow rate of water and distance moved by the sphere in my experiment.
I am a high school student writing a 4000 word...
TL;DR Summary: why do we need input length in fluid's dynamics
What is the purpose of calculating the inlet lengths of a fluid circulating in a pipe? and how to calculate it correctly? why do we need it in engineering? This is for a class project where we are asked to calculate it and I think...
Hello everyone!
I have to study for an exam, of which I have just retaken the subject (fluid dynamics) and I don't feel very good.
In my language (Spanish) I find these similar problems, but in English I only find problems that do not include these types of arrangements.
I know that the...
i have successfully transformed the continuity equation using coordinate transform,but having trouble with the momentum equation .
can someone kindly provide the transformation of the right hand sight of equation of the image i have attached.
I'm wondering what the potential benefit would be to having a fighter pilot surrounded by fluid in the cockpit on their ability to withstand high G maneuvers. How do the mechanics of fluid dynamics interact with the forces of gravity and the physiological stresses on the pilot during high G...
I am trying to follow a derivation of the Rankine-Hugoniot equations in a paper by Peter Krehl titled:
The classical Rankine-Hugoniot jump conditions, an important cornerstone of modern shock wave physics: ideal assumptions vs. reality
This paper talks about the RH equations which relate...
Hi,
In my textbook the author say that the drag coefficient is the drag force divided by the pressure at the stagnation point time the area perpendicular to the stream.
##c_d = \frac{2F_d}{\rho v^2 A}##
To get the pressure at the stagnation point I'm using Bernoulli for an incompressible fluid...
Homework Statement: Calculate the power of heating source required in a heat exchanger
Relevant Equations: Heat transfer for LMTD heat exchanger.
I have a real-world problem whereby:
Water is flowing at a constant flow rate of 10 mL/min through a PVC tube, inner radius of 1.25mm and outer...
Hey there,
First of all, all energy conservation equations for a fluid I found on google hadn't the ##\gamma## coefficient. What exactly is the difference?
Secondly, by substituting e by ##e = \frac{1}{\gamma -1} \frac{p}{\rho}## in the following equation ##\frac{De}{Dt} + (\gamma - 1)e \nabla...
Even as a layman, I've been fascinated with the structure and activity of water for years. And after reading this paper, I thought testing the electrostatic repulsion of water on a hydrophilic surface would be an interesting experiment. I'd like to see if the water droplet starts dispersing into...
Hello --
I am working on a project where I need to recirculate a fluid which has a large quantity of glass spheres of say, 1mm diameter suspended in it, but without the pump crushing the spheres. I would appreciate any advice.
To give a simple description of the desired function: it will be a...
Greeting,
I have been noodling on this problem for a bit and was hoping to have some input from this form. what volume of compressed air, at 200 PSI, will it take to push lets say 30 gallons of water 8 feet up a 3/4" pipe at a minimum of 8 gpm with a minimum pressure of 8psi at the top if...
Callen asks us the following question in his famous textbook:
I have answered as follows:
However, I get the wrong answer and, in fact, the correct answer obtains from using ##\Delta P = -\rho_s g h##; that is, using the solid density for the change in pressure. Now why on earth should this...
I'm currently searhing for a magnetohydrodynamics simulator to study how different molten metals interact with variating magnetic fields, is there any free (preferebly) simulator that someone recomends in particular?
And also, is there any way to use Autodesk's CFD to create a MHD simulation?
I'm a HS student so please dumb it down. I'm looking into the Reynolds number of a sphere sinking in a fluid, and I want to determine whether my results meet creeping flow or not Re<<1, here's what I got. **sorry if I misused the prefix, I'm not sure whether it's highschool or undergraduate**...
I tried to use this equation, so I isolated the delta h because that is what im solving for and then I thought because the pressure on both ends of the reservoir is both atmospheric pressure the change in pressure is 0. This makes my entire equation 0 and thus height is 0 which is definitely not...
Let me start off by saying that I have found (or is given) all of these: ρ, Q, V1, V2, P1, P2, A1, A2 (V being the velocity here). So no problem with Bernoulli or the Continuity equation calculations.
I am just struggling with drawing the FBD in order to evaluate the axial force, Fx
I know we...
In the following%3A%20https://pubs.rsc.org/en/content/articlehtml/2013/sm/c3sm00140g?casa_token=3O_jwMdswQQAAAAA%3AaSRtvg3XUHSnUwFKEDo01etmudxmMm8lcU4dIUSkJ52Hzitv2c_RSQJYsoHE1Bm2ubZ3sdt6mq5S-w'] paper, the surface velocity for a moving, spherical particle is given as (eq 1)...
I am a high school student trying to carry out an experiment about fluid. Thus I am studying Knudsen flow and come up with following questions.
1. How can a Knudsen flow occurs?
2. Can I simply dig a small hole on a board and make Knudsen flow?
3. What the difference between viscous flow...
Dear All,
I tried to solve the attached question. it's about Couette flow, where the 2 plates move.
in fact, I have to find the stability condition. is someone familiar with this and can help?
many thanks,
uria
Hello everyone, I need your help.
A teacher once told me that blood is a non-Newtonian, rheopectic, pseudo plastic fluid.
I get the non-Newtonian/pseudo plastic part, but I can't understand why blood is rheopectic...is it or not?
Thanks
TL;DR Summary: Need help coming up with ideas to present a current thesis in terms of qualitative and quantitative ideas.
Hey!
I have a problem. I have picked up on a project for which I am planning on doing my bachelor's thesis on. The guy behind the project is not a physicist, per se, as he...
I solved the case where m=0.99999. Then the height at which it overflows can be obtained with the equation, when points on the liquid surface are chosen. Then the cross-sectional area is given by the circumference of the circle times the height that the parabola reaches, that cross-sectional...
Greetings,
I've come across lots of exercises regarding Bernoulli's equation. However, never seen one where the top of the vessel is closed, and fluid flow exists via gas (air) going in. Has this problem been studied in the past?
Assume a cylindrical vessel filled to the maximum with a D-sized...
Suppose you have a jet of fluid (say water) traveling vertically upward at a constant velocity. It impacts a stationary horizontal plate and so moves radially outward in all directions. Assume that there's no energy loss during the impact, so the speed of the fluid remains constant. Is momentum...
Hello!
I have a question regarding the application of the bernoulli equation and calculation of the flow through a parallel pipe branch. It's more the basic understanding how the flow will establish.
You can find a sketch attached to follow my explanation.
Let's assume I have a pipe with...
Because my little work project involves fluids I thought this the best topic to post under.
I took the route of biological sciences and computer science. This area is out of my league at the moment I'm not sure the amount of time that would be required to get the material applicable to this...
Summary: doesn't this decrease entropy ?
Cellulose is known for its hydrophilic quality, which can be explained from the polarity of its hydroxyl groups.
We all know water can overcome the force of gravity through a piece of paper you put in the water.
Correct me if I'm wrong but this is a...
When we talk about sound waves in a fluid (air, water e.t.c.) we mean that the pressure ##P(x,y,z,t)## satisfies the wave equation, the so called velocity field of the fluid ##v(x,y,z,t)## satisfies the wave equation or both?
Been reading Rocket Propulsion Elements 9th Edition and got approval from my university to design a bi-propellant liquid fuel rocket engine for my senior design project, and I've been understanding everything so far but I haven't quite found an answer to how the pressure works throughout the...
I am trying to mathematically prove the Static Pressure Head equation:
H = p/ρg
How can I prove this equation and thus determine the nature of the relationship between these variables?
I want to model the advection of debris rock layer with a thickness hd on top of a glacier through ice flow with velocity components u and v. Can anybody explain the physical difference between these 2 equations and which one I should take? Thanks
Hi all,
I have some data from an automatic weather station, with recordings of both 2m air temperature and 2m air pressure and also the surface temperature. Is it possible to estimate vertical wind speeds between the AWS and the surface based upon this data? Imagine T_a = 15 degrees and T_s =...
Background
A MIDI breath controller converts breathing to MIDI values, which are then used to control a MIDI instrument and produce sound. The ones I'm familiar with work through the use of a pressure chip.
For example, the TEC Breath and Bite Controller 2 uses the MPCV5010GP...
Assume that we have a 1.5 km x 100 cm^2 long straight pipe, totally inelastic and full of water. From time t = 0, a pressure of 300 000 Pa is continuously applied to the water with a piston at one extremity. This correspond to a force of 30 000 N on the pipe cross section in the direction of the...
Ocean physics explain cyclones on Jupiter
https://phys.org/news/2022-01-ocean-physics-cyclones-jupiter.html
Moist convection drives an upscale energy transfer at Jovian high latitudes
https://www.nature.com/articles/s41567-021-01458-y...
I saw this in a textbook and I thought it is a corollary of Reynold's transport theorem. Let \mathbf{F} be a smooth vector field Consider the surface integral:
\int_{S}\mathbf{F}\cdot d\mathbf{S} and now take the derivative of it, then the expression can be written as...
If one Googles for "laminar flow nozzle", one finds many interesting tutorials on creating a nozzle for a laminar water jet; a stream of water that remains coherent over a long distance without breaking up. These typically consist of a large-diameter tube with regions inside (like sponges and...
According to Cauchy's stress theorem, the stress vector ##\mathbf{T}^{(\mathbf{n})}## at any point P in a continuum medium associated with a plane with normal unit vector n can be expressed as a function of the stress vectors on the planes perpendicular to the coordinate axes, i.e., in terms of...
Hi!
Water is flowing in a converging duct, with the angle α, see the figure.
My task is to find a real-life phenomenon / application of this model, and later solve it numerically / analytically where this fluidproblem occurs. However, my imagination is kinda slow today, what are some fun /...
I'm currently working on a precise glue/resin dispenser, and I'm trying to derive an equation for the force one must exert on a syringe plunger as a function of the desired flow rate Q, and also accounting for the fluid viscosity and the syringe barrel and needle geometry. I've attached a scan...
Previously, I have seen the derivation of the energy conservation equations for simulation of single phase flow in a porous media (a packed bed). These are the energy equations for the solid and fluid respectively:
I understand the derivation, however, these equations will only work when the...
In my first attempt, I started off converting the radii of all three sections from centimeters (10, 8, 6) to meters (0.10 , 0.08 , 0.06), then used the VFR=Av formula to find the speed/velocity of section one.
VFR== 0.063 m^3/s
A== pi*r^2=pi*(10cm)^2=pi*(0.10)^2=pi*0.01 == 0.031415927
VFR/A=v...