# fluid

1. ### B Underwater thrust formula?

I'm trying to determine the force needed for one object to displace another object underwater. Specifically, Object A strikes Object B hard enough to jettison it from the seafloor up to sea level/land, let's say the Pacific coastline. I have a timeframe in mind, density & mass of the two...
2. ### I Normal Stress

What's really the difference between pressure and normal stress? Also I know pressure acts normal to a surface from the outside Do normal stress acts from inside? I'm reading bird transport phenomena and this is confusing
3. ### Tube immersed in alcohol

This is a problem from a past exam. For point a) the balance between force should be given by the following equation $$M*g+p_0*A=ρ*g*(A*d)+p*A$$ But I still have two unknown values... I know that pressure outside the tube at depth d is $$p(d)=p_0+ρ*g*d$$ and this has to be equal to the...
4. ### Hole Sizing to Drain Fluids [Pressurized Container]

Hello, I want to size my system to be able to get rid of fluids without any head buildup within the container. I am just a bit confused as to what formula I should use. My problem is summed up in the following schematic. Note that P1>P2, I have assumed H=10^(-4)m and my flow rate is 0.1 m3/s...
5. ### I Misting system

I am attaching a standard 5/8" garden hose with approximately 70psi pressure to a copper pipe that is capped on the opposite end with mist nozzles mounted periodically along its length. I want the pressure at each mister to be as similar as possible. The hose attaches at the base, a solid line...
6. ### Bouyancy force -- What mass can the balloon carry?

In a I used FBouyancy - FBalloon -F mass = 0 rewrote mass as a product of density and volume to obtain; m= v(densityair - densityHe) m= 1031.5kg. I am stuck in part b. I have this formula called Barometric formula which ı should use; P = P0 * e((-P0*g*h)/ P0 So what I understood is...
7. ### I Subsonic and Supersonic Airflow Through a Constriction

Hi everyone! For the past week I have spend a lot of time thinking about how de Laval nozzles work. But before I convince myself that I have understood it, I want to make sure that the (simpler) scenarios I describe below are correct. Setup: We have a long pipe with constant radius r = 1...
8. ### I Trying to better understand what viscosity really is

I'm trying to get a better handle on the actual physical phenomena underlying viscosity (for newtonian fluids). Something I could word in the format of "this happens (and this and this), and so the fluid resists flow." What I've found online is that when gasses are at higher temperatures, they...
9. ### I Pascal's law (fluids): Derivable from fundamental laws?

Hi. Pascal's law states that static pressure in a confined incompressible fluid without gravity is the same everywhere. Is this law derivable from more fundamental laws? Some thoughts: Is Pascal's law part of the definition of the liquid state? If the liquid operates between two hydraulic...
10. ### Pressure inside the zeppelin for it to float

1. Homework Statement A zeppelin of an ellipsoid shape (a=32m, b=c=a/3) iz filled with hydrogen. Pressure of the surrounding air is 100 000 Pa. Temperature of air and hydrogen is 20°C. The mass of an empty (not filled with hydrogen) zeppelin is 10 000 kg. What does the pressure of hydrogen...
11. ### B How can I model a density function of a compressible fluid?

I have a cylinder of some dimensions. I have a compressible liquid inside. Assuming a constant temperature, no atmosphere, no convection currents within, because it is in a cylinder, there will be no variations in density horizontally (the fluid will have time to settle). Now because there is...
12. ### Pressure at the bottom of a container containing two liquids

1. Homework Statement (In the attachment)There is two layers of liquids in the container .The density of the upper layer of the container, $ρ_1=800kg/m^3$ and the density of the bottom layer of the container ,$ρ_2=13600kg/m^3$ .What is the pressure at the bottom of the container? 2...
13. ### Fluid static problem with wooden block being pulled down

1. Homework Statement The figure below shows a metal object (2) hanging by a thin cord from a floating wooden block (1). The wood block has a SG of 0.3 and dimensions of 50mm x 50mm x 10mm. The metal part as a volume of 6600m^3. Find the mass of the metal part and the tension in the cord. Work...
14. ### Application of Pascal paradox

1. Homework Statement The points of interest are at point A and B, I want to calculate the pressures at that point. I am working in gage pressure so we can ignore atmospheric pressure. 2. Homework Equations P = pgh P = sg x specific weight of water x height 3. The Attempt at a Solution...
15. ### Circular duct problem

1. Homework Statement Shown in the figure attached. Circular duct with a diameter of 150 mm, strikes a cup and exits through a circumferential slot to the atmosphere. Mean velocity in the duct = 100 ms^-1 Air density = 1.1 kg/m^3 Dynamic viscosity of air = 19.05 x 10^-6 kgm^-1s^-1 (a)...
16. ### Polytropic process question

1. Homework Statement At the start of a compression, a cylinder contains 0.04 m^2 of some ideal gas at a pressure of 100kPa and a temperature of 110 degrees. Compression takes place according to the law: P(V)^1.27 = constant The gas undergoes a two stage process: compression from 0.04 m^3...
17. ### B Will water flow ever stop if we increase resistance?

Complete question: Will flow ever reverse or stop if we increase resistance in this pipe scenario? There are 2 comunicating vessels. The highest vessel is coninuosly alimented with new water. Water in excess flows down on the sides. Water will try to reach the same height in both vessels...
18. ### I Different answers from equation of continuity and Bernoulli

Hi there, So I was doing the dishes this morning using a sink wand hat can toggle between different flow speeds. The way that I've always thought of this working is using the equation of continuity: Volume flow rate: = Area*velocity Pressing a button on the wand decreases the cross-sectional...
19. ### Fluid Dynamics -- Use the Milne-Thomson circle theorem to show the complex potential for a fluid...

1. Homework Statement Two equal line sources of strength k are located at x = 3a and x = −3a, near a circular cylinder of radius a with axis normal to the x, y plane and passing through the origin. The fluid is incompressible and the flow is irrotational (and inviscid). Use the Milne-Thomson...
20. ### Fluid Dynamics -- Find the maximum possible flow speed on the streamline...

1. Homework Statement At point A in the flow of a compressible fluid, the flow speed is 100 m s−1 and the Mach number of the flow is 0.6. Find (i) the maximum possible flow speed on the streamline through A, and (ii) the flow speed at a point where the pressure has fallen to half its value at...
21. ### MATLAB Coding angular spectrum of waves in a fluid

Hi, I am trying to code ultrasonic transducer radiation in water using angular spectrum of plane waves. I am having difficulties in the sampling and fft. If anybody has an idea about this can you please help me out? I can paste the code once i get some response. Thanks for your help!
22. ### Compute Fluid drag, Swim Physics

Hello, I'm trying to create a simulation of swimming "Animats" (artificial animal). However, I'm only an high school student, so I don't know how to deal with fluid drag and fluid dynamics. In this link you could find a short animation I made describing the swim motion my animat is going to...
23. ### At supersonic speed, why does Mach number decrease?

At supersonic speed, air become compressible. However why does Mach number decrease when flow area decrease? I understand that pressure will increase because the density will increase when flow area decrease. However shouldn't the Mach number increase in order to conserve mass flow? Unless the...
24. ### Finding the density inside a tank as air escapes

1. Homework Statement A tank of constant volume V contains air at an initial density pi. Air is discharged isothermally from the tank at a constant volumetric rate of Q (with SI units of m^3/s). Assuming that the discharged air has the same density as that of the air in the tank, find an...
25. ### I Stream inside paraffin oil when exposed to high volage

Here is the experience: I put two electrodes inside paraffin oil (separated by at least 3cm), and submitted the electrodes to high voltage. At 20000 V - 30000 V, strong streams can be observed inside the paraffin oil. Since paraffin oil is a good dielectric, I just would like to understand the...
26. ### B Modelling water tanks

I tried using the Bernoulli equation to solve this. I took two points at the surface of the water in both the containers and formed this equation: gh_{b}=\frac{1}{2}v^2+gh This is assuming that the velocity of the water in the large tank is approximately zero and using the fact that both the...
27. N

### Pressure at the center of an accelerating sphere

1. Homework Statement Consider a glass sphere completely filled with water except for a small air bubble at 1 atmosphere. The sphere is accelerating to the right. What is the pressure at the center of the sphere? Let Pe = Atmospheric pressure r = radius of sphere pw = density of water a =...
28. ### B Liquid pressure in a cone

I am confused about the pressure depending only on the depth of the liquid, particularly for a cone. Up until P=mg/A=ρVg/A I understand it, but the problem I have is cancelling the area with the volume to give the height. How does this work when the volume of the liquid in the cone is not given...
29. N

### I Internal pressure due to vessel collapse

Hey All, I have a plastic vessel fully filled filled with an incompressible fluid (Water), at some time this vessel is impacted and crushed on one side (say 5% of the initial volume is lost). Only, I know the volume isn't lost, the fluid (being incompressible) will exert pressure on all...
30. ### Mean section method

1. Homework Statement I have problem of obtaining the cross sectional area . 2. Homework Equations 3. The Attempt at a Solution Taking section 2-3 as an example , my working is [ (3.3 +4.8) / 2 ]* 5 = 20.25 , but the ans provided is 29.28 , how to get the 29.28 ?