Fluid dynamics Definition and 609 Threads

I'm thinking about the following problem. I have an electrified fluid with a constant charge density, Q, within the fluid. Will this necessarily yield a surface charge? Would I have to compute it by looking at the displacement fields on either side of the interface? Would it change if the bulk...

Hello everyone! I am planning to make an irrigation system for our new hedge by drilling small holes (1mm diameter) in a 1/2 inch hose. The hose will have a length of approximately 28 meters and there will be one hole every 30cm, so about 93 holes in total. The water will be coming out of the...

Imagine a firetruck with a hoseline attached to the pump. The pump is set to 800kpa with 100kpa loss due to friction in the 30m hoseline so you have 700kpa at the nozzle. What would the pump's gauge read if you disconnected the hoseline? I thought since there is no more resistance, the...

If you imagine putting your thumb at the end of a garden hose and slowly restricting the area until the area is 0, according to the continuity principle, the flow rate stays constant because the velocity increases to make up for the smaller area. However obviously this can't be completey...

Hi, I'm have been trying to model an airsoft replica, as an electrical engineer fluid dynamics, thermodynamics is a complete new flied for me and with with help of Ai i have been learning a lot about this subject. So far I have come a long way in making something my first model sort of worked...

Homework Statement: Sorry there is no homework statement with this problem Relevant Equations: n/a Hi guys. This is my first post here. I love physics but I am unsure how do model water flow type of problems. If anyone could please help us with how we can analyse this it would be much...

Hello, I am an electrical engineer but was tasked with something a little different this time around and was hoping you guys could help. I would like to determine if my dry air system is sufficient for my purposes and I would like to accomplish that by determining flow rate in CFM. I have been...

If this formula were to be correct, if we use the liquids in the Venturimeter and the tube to be of the same density, the velocity would come out to be zero which makes no sense. I calculated the formula and got a slightly different numerator. Am I correct?

Greetings, I need to work out the flow rate of of a flow through an orifice, where the size of the orifice and differential pressure are varied. The primary unknown in working out flow rate is the coefficient of discharge. A textbook I've been using to help me is "Hydraulic Control Systems" by...

I'm 64. My background prior to 2001 - Aviation, experimental aircraft and aerodynamics, robotics, mechanical and software engineering, disaster recovery. Since 2001 - Human sustainability and global recovery, researching every related sector in depth in order to understand what can now be proven...

I asked this question about one year ago, but at that time I didn't really understand what I was doing. After spending a lot of time in this problem, I still fail to get the asked answer. Starting with ##\frac{De}{Dt} + (\gamma - 1)e \nabla \cdot \vec{u} = - \frac{1}{\rho} (\vec{u} \cdot...

Hello everyone 😊, I know that shear stress in turbulent flow is a lot larger from shear stress in laminar flow. My question is about the shear stress at the walls of the pipe. So i was watching a video about shear stress in turbulent flow and the narrator pointed out that the shear stress in...

Across a horizontal pipe with fluid flowing inside, the pressure will drop due to the friction between the fluid and the pipe walls So if for example the fluid flows from left to right and we take 2 points: P1 (pressure on the left) and P2 (pressure on the right) then P1 should be bigger than...

Hello everyone 😊 Let's say, we are having laminar flow in a cylindrical pipe. The fluid in direct contact with the pipe doesn't move (no slip condition), so there is no sliding between the surface of the pipe and the surface of the water. The friction that occurs is actually between this...

TL;DR Summary: We know that the fluid pressure at the exit of the pipe is Patm but what about before the exit? How can we calculate that pressure using Bernoulli's equation. Hello everyone☺️. Please help, i'm seriously stuck 🫠🙇‍♀️ When learning about bernoulli's equation there's a classic...

The pressure is easily calculated from equation of continuity and Bernoullis theorem: $$A_1v_1=A_2v_2\implies v_2=16ms^{-1}$$ SInce pipe is in horizontal plane, no difference in pressure because of height $$P_1+\frac{\rho v_1^2}{2}=P_2+\frac{\rho v_2^2}{2}$$ $$P_2=172\times 10^3$$ What I...

I'm trying to find how the author finds the boundary condition at ##r\to\infty## is ## \Phi(r,\theta, \phi) = - V r cos \theta##. Using the spherical coordinates. ##- V \hat{z} = \nabla \Phi## ##- V ( cos \theta \hat{r} - sin \theta \hat{\theta}) = \frac{d \Phi}{dr}\hat{r} + 1/r \frac{d...

Asking on behalf of a colleague who is studying rainwater transport/drainage in the context of plants (trees, mostly): There's a lot of published work analyzing the flow of fluid within a tube, or along an interior corner. I can't seem to find much of anything about the flow of water along the...

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...

ref. answer Q： Why ρ1≠ρ2≠ρ3, but the answer says ρ1Q1+ρ2Q2=ρ3Q3 can be simplified into Q1+Q2=Q3?

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...

I have tried to approach in the following way I am stuck. How should I approach this next.please help

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...