# What is Fluid force: Definition and 30 Discussions

Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them.:3
It has applications in a wide range of disciplines, including mechanical, civil, chemical and biomedical engineering, geophysics, oceanography, meteorology, astrophysics, and biology.
It can be divided into fluid statics, the study of fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion.:3
It is a branch of continuum mechanics, a subject which models matter without using the information that it is made out of atoms; that is, it models matter from a macroscopic viewpoint rather than from microscopic. Fluid mechanics, especially fluid dynamics, is an active field of research, typically mathematically complex. Many problems are partly or wholly unsolved and are best addressed by numerical methods, typically using computers. A modern discipline, called computational fluid dynamics (CFD), is devoted to this approach. Particle image velocimetry, an experimental method for visualizing and analyzing fluid flow, also takes advantage of the highly visual nature of fluid flow.

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1. ### How far will the bottom gate of a reservoir open?

<Moderator's note: Upload images to PF. Do not use an external image server.> I got an expression for the angle taking that initially the gate is closed, so the gate has h, W and L as their dimensions. So there is a surface integral to find the resultant force applied on the gate, using the...
2. ### Construction How do you build a self-submersible boat?

So I've been thinking for a long time now about making a self-submersible boat out of a plastic bottle without electronics. It should resurface by itself after a few minutes. I was thinking that it might increase its volume. By slowly dropping weights down the bottle and opening flaps on the...
3. ### I Fluid force from a fluid flow vs. from a fluid jet

In fluid flow (such as wind), the force exerted on a perpendicular surface is derived from kinetic energy and is ρAv^2/2. But in problems involving a jet of fluid that strikes a plate, the force is derived from momentum and is explained to be ρAv^2, lacking the 1/2 factor. Can someone please...
4. ### Shear stress direction and the velocity gradient

1)In a flowing fluid in laminar fashion we know that it flows in planes which slides over each other, Let's take a fluid element (cylindrical) in a pipe(Radius=R) the resistive force is (stress)(cross section area of cylinder with radius 'r') acting in backward direction, now if I take Flow...
5. ### Fluid force at the end of a pipe

Consider the very standard pipe problem used to calculate the force required to hold a pipe with a bend that has some fluid flowing through it, as shown in the image. We use Newton's second law of motion to calculate the external force required. However, why is there pressure acting into the...
6. ### Area of common surface of two bubbles

What will be the area of common surface of two identical bubbles of radius R , i know there common surface will be flat as the radius of curvature of comman surface will tends to Infinity , but how do i relate with area of flat surface I tried to use Energy = Surface tension * area And then...
7. ### How to find the resultant force in a T tube section

Homework Statement So, I need to find the X and Y components of the force in the T section Homework Equations Due the fact that the problem dosn't ask for a specific force I couldn't think in any other equation to use, because even tough there is Pressure and Gravity acting I need to...
8. ### Fluid mechanics civil engineering

As shown in the attached image, a tank has an inclined wall at an angle of 450 to the horizontal. On this wall, there is a 1m square door that is hinged at A and has a simple latch at B. The distance between A and the free surface of sea water measured along the inclined wall is 2 m. (Specific...
9. ### Trouble with a basic fluid force problem

What is the pressure on a horizontal surface with an area of 2m^2 that is 4m underwater? I tried to just use the formula: Force= (Density of water)(Area)(Depth)(gravity), plugging in the values Force=(1000kg/m^3)(2m^2)(4m)(9.8m/sec^2) and get 78400 N, when in reality the real answer is...
10. ### Describe movement of particles with one equation?

Hello everybody, I have a new thread to post,it is very important to find a solution for this : -Imagine a box full of air particles.The particles are forced to move to a point A on the edge of the box.My question is now,how can I mathematicly describe the movement of these particles toward...
11. ### Integration: force on submerged triangular plate

Homework Statement Submerged (vertically) right triangle 12x9x15(hypotenuse) with 12 m leg parallel to water surface. Top of triangle is 3m below surface. Find force on triangle.[/B]Homework Equations I know mass of water is 840 k/m3. I think I should also multiply times 9.8 for gravity...
12. ### Help solving / check fluid force

I have a vertical panel. Top of panel is at water level. Units are in feet. 15'x5'. I calculated the force in pounds. water=62.5 lb/ ft3. I came up with F= 11,718.75 lb Just double checking this, making sure I did I correctly.
13. ### Calculating Fluid Force of Triangle Submerged in Water

Homework Statement Find the fluid force of a triangle with base of 6 ft and height of 4 ft submerged vertically into a body of water,vertex down, to a depth of 3 feet. Homework Equations from c to d W ∫ h(y) L(y) The Attempt at a Solution I set up the triangle on an x and...
14. ### Fluid Force (Real-Life application) Find my error

So I'm in the Navy. I work on an aircraft carrier that just went into drydock. The drydock has a large trapezoid door keeping the water out on one side. Our captain wants to know how much force is being held back on that door. I found the dimensions of it and calculated it, but now I'm having...
15. ### Fluid force on a dam just trying to reason with the problem

Homework Statement A dam is shaped like a right triangle, 4 height and 6 across. The right triangle is oriented so that the right angle is at the TOP RIGHT. (we are looking at the face of the dam) Density is a weight density, and is 64 lb/cubic foot Homework Equations The...
16. ### Work and Fluid Force, lifting water out of a triangular prism tank

Homework Statement A vertical cross section of a tank is shown. Assume the tank is 16 feet long and full of water. (\delta=62.4, and that the water is to be pumped to a height of 8 feet above the top of the tank. Find the work done in emptying the tank. The tank is a triangular prisim with...
17. ### Fluid force integration problem

Homework Statement The vertical triangular plate shown in the picture below is the end plate of a feeding trough full of hog slop, weighing 80 pounds per cubic foot. What is the force against the plate? Homework Equations This question is supposed to involve intregration to find...
18. ### Calculating Fluid Force on Circular Plate in Water Tank

Find the fluid force on the circular plate shown in figure (see attachment). Assume the plates are in the wall of a tank filled with water and the measurements are given in feet. F=w∫h(y)L(y) dy I have that h(y)= 7-y and L(y)=2√(4-y^2). Therefore, F=2(62.4)∫(7-y)√(4-y^2) dy from y=0 to...
19. ### Maximizing Fluid Storage in a Rectangular Tank with Given Force Limit

Homework Statement This is just a general question. The questions I can't get go something like this: You're given a liquid you plan to store, in a tank, say for this example, a rectangular one with square sides. You're given the max fluid force that the interior walls can withstand, and...
20. ### Finding Fluid Force on Plate Submerged in Fluid

2. A plate shaped as in the figure [picture.jpg is attached] is submerged vertically in a fluid as indicted. Find the fluid force on the plate if the fluid has weight density 62.4 lb/ft^3 The integral I set up was the limits being -5 to -1 and the integral being (5-y)(-7/4y - 7/4) dy...
21. ### Work and Fluid Force: Calculus II

I worked out these two problems and got an answer but was not sure about the answer... If you could just check it and if it is not write tell me what I did wrong or give me a step by step, it would be greatly appreciated. 1. A tank is formed by revolving y = 3x^2, x = [0,2] around the...
22. ### Help solving Fluid Force problem

Homework Statement A 2.20m wide tank is filled with water totaling 1.87m (H1). There is a hatch cosisting of a portion of a wall of the tank which is 1.15m(H2) in length (measured from the bottom of the tank). What is the Force on the hatch resulting from the water?Homework Equations F =...
23. ### What causes a change in wind direction when it hits a sail?

I'm trying to make a computer simulation of ship. Currently I'm working on a force of wind on the ship sail. This is the page which describes the basics: http://www.animations.physics.unsw.edu.au/jw/sailing.html Basicaly, wind (W - vector) has some staring direction and then that...
24. ### Fluid Force. Help exam today

A metal oil tank has cross-section that is a square rotated 45 degrees as shown in the figure above. Its height is 12 ft and width is 12 feet. The oil in the tank has a weight-density of 57 lb/ft3. Write a definite integral that expresses the fluid force on the end of the tank when the oil is...
25. ### Calculating Fluid Force on a Circular Pressure Release Gate in a Dam

Homework Statement A circular "pressure release gate" is located in the vertical face of a dam. The radius of the gate is 2 metres and the gate is positioned so that its top lies 5 metres below the surface of the water held in the reservoir behind the dam.Find the total fluid force acting on...
26. ### Volume of solid and fluid force

Homework Statement find the volume of the solid generated by rotating the circle (x-10)^2 + y^2 = 36 about the y-axis Homework Equations disk method: \pi\int [R(x)]^2dx shell method: 2\pi\int (x)(f(x))dx The Attempt at a Solution y = \sqrt{36-(x-10)^2}dx[\tex] \\\pi\int...
27. ### Fluid Force Problem- Caclulus II

Problem: A porthole on a vertical side of a submarine submerged in sea water has a diameter of 2r feet. Sea water has a weight density of 64 pounds per cubic foot. Find the fluid force on the porthole, assuming that the center of the porthole is d feet below the surface. Relevant Equations...
28. ### Fluid Force Problem: Find the Answer with Help from Dean

I would appreciate any help I can get w/the following problem: A square plate of side 'a' ft is dipped in a liquid of weight density 'p' lb/ft^3. Find the fluid force on the plate if a vertex is at the surface and a diagonal is perpendicular to the surface. I understand the surface has a...
29. ### Fluid Pressure and Fluid Force in Calculus II

Hi. I need help on how to set up the integral for these problems. 1. A cylindrical gasoline tank is placed so that the axis of the cylinder is horizontal. Find the fluid force on a circular end of the tank if the tank is half full, assuming that the diameter is 3 feet and the gasoline...
30. ### How Is Fluid Force Calculated on the Bottom of a Trapezoidal Pool?

Let us define a pool. Viewed from top, we see a rectangle of sides 16 ft and 10 ft. When we look from the side (so the 16 ft side is perpendicular to our view), it is a trapezoid with width 16 ft and 4 ft, 16 ft being the height. It is roughly like this: From top: 16 ft...