What is Fluid: Definition and 1000 Discussions

FLUID (Fast Light User Interface Designer) is a graphical editor and GUI builder that is used to produce FLTK source code. FLUID edits and saves its state in text .fl files, which can be edited in a text editor for finer control over display and behavior.After designing the application, FLUID compiles the .fl file into a .cxx file, which defines all the objects from the .fl file, and an .h file, which declares all the global ones. FLUID also supports localization of label strings using message files and the GNU gettext or POSIX catgets interfaces.

A simple program can be made by putting all non-interface code (including a main function) into the .fl file, thus making the .cxx file a single source file to compile. Most programs are more complex than this, so other .cxx files can be written that call the FLUID functions. These .cxx files must #include the .h file, or they can #include the .cxx file so it still appears to be a single source file.
Normally the FLUID file defines one or more functions or classes, which output C++ code. Each function defines one or more FLTK windows, and all the widgets that go inside those windows.
Widgets created by FLUID are "named", "complex named", or "unnamed". A named widget has a legal C++ variable identifier as its name (i.e. only alphanumeric and underscore), and is defined by a global variable or class member that will point at the widget after the function defining it is called. A complex named object has punctuation such as '.' or '->' or any other symbols in its name. In this case, FLUID assigns a pointer to the widget to the name, but does not attempt to declare it. This can be used to get the widgets into structures. An unnamed widget has a blank name and no pointer is stored.
Widgets may either call a named callback function that one writes in another source file, or one can supply a small piece of C++ source and FLUID will write a private callback function into the .cxx file.

View More On Wikipedia.org
Recent contents Top users
  1. K

    Van de Waals fluid in Free energy, Enthelpy representations

    Compute the coefficient of expansion α in terms of P and V... Homework Statement Compute the coefficient of expansion α in terms of P and V for an ideal Van der Waals gas Homework Equations (p+a/v^2)(v-b)=RT The Attempt at a Solution Is this as simple as solving for a? How...
  2. D

    Question about fluid dynamics (calculating concentration)

    Hi all, I have a question about calculating the concentration of continuous air and carbon monoxide flowing through a pipe. If the gas cylinder originally has 20% CO and 80% air and it will be diluted by another gas cylinder of air, how do you account for temperature, pressure, and...
  3. T

    Fluid mechanics - Conservation of mass problem

    Homework Statement Here is the question along with my attempt: As you see in my second equation there are two unknowns, A_out and dm/dt. I think my problem is that I don't exactly understand the equation. dm/dt is the net mass flow rate. For example if dm/dt is a positive number then there...
  4. M

    Adding stirring force acting on the fluid

    when you stir fluid in a beaker of fluid, how is the motion on the fluid by the stirring rod calculated? the fluid is represented using smoothed particle hydrodynamics lagrangian method so that I can look at fluid as a bunch of spheres interacting with each other through a sort of force...
  5. T

    Plasma Fluid Mechanics - Convective Derivatives

    Homework Statement Use the continuity and momentum conservation equations for a single species to construct the following "convective derivative" equation for the fluid velocity: \frac{\partial\vec{v}}{\partial t}+\vec{v}\cdot\nabla\vec{v}=\vec{g}-\frac{1}{\rho}\nabla p...
  6. D

    Question about fluid flow and pressure in pipes

    Does a pipe have to be completely filled with a fluid to measure its pressure? For instance if I have a small diameter pipe that diverges to a bigger pipe. The small pipe will be completely filled with water, but will the bigger pipe be? If the bigger pipe is only half full of flowing water...
  7. A

    FLuid Flow through a Divergent Section

    Hi, Can Someone Elaborate the fluid(water) Characteristics Such as Velocity n pressure When it passes through a divergent Part. Actually The Fluid is pumped Out from A 0.5HP Centrifugal Pump and then made to pass through a Divergent Part.
  8. Astronuc

    Computational Fluid Dynamics by John D. Anderson

    Author: John D. Anderson Title: Computational Fluid Dynamics: The Basics with Applications Amazon Link: https://www.amazon.com/dp/0070016852/?tag=pfamazon01-20 Prerequisities: Calculus, Introductory Physics and/or Aerospace Engineering, Fluid Mechanics, Heat Transfer Level...
  9. J

    Fluid Mechanics Problem Creating a Mesh

    We are beginning a project in my Intermediate Fluids class to make a program that can do aerodynamic analysis on an air foil. First, given any three nodal coordinates (x,y) of a triangle, we must write a program to compute its surface vectors and area of the triangle. The nodes will be in...
  10. B

    Basic Fluid Dynamics: Calculating Exit Velocity & Mass Flow Rate

    Hi guys and girls, I hope you can help an electronics engineer out of his place in the mechanical world:uhh: My very basic question is for a vessel holding a liquid at a given pressure and a given opening in the vessel how can i calculate exit velocity and mass flow rate? Like if i blow a...
  11. J

    Probability fluid velocity and quantum entanglement question

    Hey everyone, I'm a second year undergraduate student in aerospace engineering and I've been learning a bit of quantum mechanics for the past few weeks, for recreational purposes. I've been following this textbook: http://www-thphys.physics.ox.ac.uk/people/JamesBinney/qb.pdf On pages 40-41...
  12. S

    Mixing of fluid streams in rivers

    Walking round a local amenity area today brought this photo of a side stream cut off by the local river in spate flowing past from left to right in the picture. The river water is reddy brown and the side stream grey-green. The two waters are not mixing as can be seen by the well defined...
  13. M

    Fluid mechanics, bernulli equation: reference points

    Can anyone give me some advice on where I should take my points of reference when using bernulli equation. I know the point will vary according to the problem, but can one say, always begin looking for this and that and apply the equation... Then move to this and that, etc
  14. S

    Fluid Dynamics - increasing pressure

    I am working on hobby project with almost no budget. I bought some "nice" (cheap & simple) electronic solenoid valves for water flow. I've since discovered that they need 3PSI to open. Which is ok for the supply lines. But the drain line requires that as well. Now I either need a column of water...
  15. L

    Calculating the average divergence of the flow of fluid in a box.

    Homework Statement A cube of side 5cm is placed in a fluid. For the following velocity values, calculate the average divergence of the flow. Is there a source or sink within this box? The velocities are given in cm/s. The cube is oriented so that the +z axis exits the front face, the +x axis...
  16. P

    I want to do an egg drop by submerging the egg in fluid. Which fluid is best?

    The basic idea is to package an egg so that it will not break when I drop it off a roof (assume 10m tall). The packaging should be as small and lightweight as possible. I know using a fluid will be rather heavy, but I'm still curious about his. How would I determine the optimal fluid to use? I...
  17. E

    Solving for the Constants in Fluid Flow through a Pipe

    Hi, I'm looking at the solution to a question on fluid flow through a rigid pipe. Original equation: \mu u = 0.25r^{2} dp/dx + Aln(r) + B After applying boundary conditions: \mu u = 0.25dp/dx (r^{2} - a^{2}) I don't understand how the constants have been solved for. Below is as far as I get...
  18. M

    Understanding bulk fluid motion under Lorentz force

    I am trying to understand how the Lorentz force affects bulk fluid motion when I have an applied electric field (y-axis), applied magnetic field (x-axis) and bulk fluid velocity (z-axis), all orthogonal to each other. I understand that if the fluid was at rest, an electrostatic force would...
  19. P

    Probability Density Functions in Fluid Mechanics

    Hi all, For an exam I'm required to be able to plot the PDF of a fluctuating velocity function, say u(t)=sint(wt), using what they call the "graphical technique", but handily I can't find it anywhere in the lecture notes, and I'm struggling to find anything with a standard Google search...
  20. M

    Predicting Lorentz force fluid particle trajectories

    I am trying to understand how the Lorentz force affects bulk fluid motion when I have an applied electric field (y-axis), applied magnetic field (x-axis) and bulk fluid velocity (z-axis), all orthogonal to each other. I understand that if the fluid was at rest, an electrostatic force would...
  21. P

    Fluid mechanics: Flow and velocity of a fluid

    I've rencently been thinking about several systems related to fluid mechanics, and I've asked myself the following question: If I have a cylidrical tank with a small hole in the bottom (the surface area of the hole is small in comparison with that from the tank) and I'm filling the tank with...
  22. P

    Weight of a fluid when I put my finger in it

    Hi. I was asking myself the following question. What happens if I have a fluid at rest inside a container, and I introduce my finger in it without applying any force to the walls? Will the weight of the whole system change? My intuition says no (If I don't exert a force on the fluid this...
  23. B

    Need help on basic fluid volume calculation

    Need help on basic fluid volume calculation! Hey guys, I need some help calculating a volume. Ok, so say we are given a pressure vessel with an 88ci volume @ 4500psi which is then regulated down to 100psi and we open a valve for 0.1 second. How many cubic inches of air would be released...
  24. B

    I need help with a Fluid Mechanics problem

    the probem is from the book: Fundamental mechanics of fluids by I.G. Currie is from the chapter 4 ( 2 dimentianal potential flows ) is the problem 4.4: . Consider a source of strength m located at z = −b , a source of strength m located at z=- a^2 / b , a sink of...
  25. E

    What causes an increase in boundary layer thickness in fluid flow?

    hi all,i have recently started studying a subject heat transfer,in which i learned that there are two types boundary layers.one is velocity boundary and other is temperature boundary layer..now my question is that..boundary layer thickness increases in flow direction,what is the physical...
  26. J

    Can any one help with this Fluid mechanics question please?

    Homework Statement A shaft of diameter 74.9mm rotates at 1400rpm in a bearing which is of diameter 75.03 mm and 75mm in length. The annular space between the shaft and the bearing is filled with oil of viscosity 0.096 kg/ms.By assuming a uniform velocity gradient in the oil, determine the...
  27. V

    Idealized Fluid: Pressure & Force Tangential to Surface

    1. The problem statement... The textbook I am using states that an idealized fluid cannot sustain a force tangential to its surface. Can anyone expound upon this argument? This statement is an introductory exploration of pressure and is cited as the reason that the force dF exerted by its...
  28. T

    What Are the Best Fluid Mechanics Textbooks for Aspiring Students?

    I am interested to know what book(s) others would recommend to someone aspiring to learn fluid mechanics from and what kind of preparation would be required for that book. I am an undergraduate student and have completed courses in single and multivariable calculus, linear algebra, ordinary...
  29. K

    Fluid mechanics: defition of shear flow [rate of deformation tensor]

    fluid mechanics: defition of "shear flow" [rate of deformation tensor] I'm studying old undergraduate chemical engineering notes for an exam in grad school. Can't recall what this really means, can anyone explain to me what "off-diagonal elements" means and why the trig function velocities...
  30. tomwilliam2

    Incompressible vs constant density fluid flow

    This may sound like a basic question, but it's just to get it clear: When describing fluid flows, does the term "incompressible" mean exactly the same thing as "constant density"? I was under the impression that if a fluid cannot be compressed, then its density must remain constant for any...
  31. E

    Fluid Statics - Forces on Submerged Surface?

    QUESTION Rainwater collects behind the concrete retaining wall shown in the figure. If the water saturated soil (specific gravity 2.2) acts as a fluid, determine the force and center of pressure on a 1-m width of the wall. PROBLEM 1. What does it mean by 1-m width of the wall? Is it 1-m...
  32. P

    Question about fluid mechanics

    Hi, I am trying to work with the problem of keeping a solid body at equilibrium over an orifice. To see what I mean ( not necessarily a sphere could be a cube or something like that as well ) please look at the image I have attached. I am trying to work with the sphere case first and then...
  33. R

    Rotating Bucket Dynamics: Oil vs. Water Surface Shapes

    Homework Statement Consider a bucket quarter filled with oil. When the bucket is rotating with the angular velocity ω, derive the equation of the surface h(x), where h is measured from the lowest of the surface and x is measured from the rotational axis. Does it change if we replace oil by...
  34. G

    What are some alternatives to lubricant oil for industrial testing purposes?

    Hi, I am a mechanical engineer, therefore I am no very experienced in chemistry I need to find a fluid similar to lubrificant oil in density and viscosity, but with low oiliness I thought to gasoline, but it is very dangerous for my aim. I have to test on the production line some components...
  35. D

    Fluid mechanics cork in water

    Homework Statement A cork is held at the bottom of a bucket of water by a piece of string. The actual depth of the cork is 0.713786 m below the surface of the water. If the density of the cork is 157 kg/m3 and the volume of the cork is 3 cm3 , then what is the tension in the string...
  36. S

    Defining Low and High Speeds in Fluid Resistance: Utilizing the Reynolds Number

    Hi all, I know that for low speeds, the fluid resistance is F=kv while at high speeds, it's F= Dv^2. However, how do I ever know what is defined as a low speed and high speed? This kind of explanation is so qualitative and I think a quantitative one is better. Thanks all!
  37. C

    Where can I learn all of this? Fluid Physics

    I've been attempting my Physics homework and realize I have no idea how to do any of the problems. Instead of asking each of them, I figured I'd ask if anyone knew where I could find a general lesson plan for this section. Here are some of the problems. All help is appreciated :). 1) A...
  38. P

    Loop of pumped fluid slowly falling into black hole.

    You have this loop of water (or some other "incompressible" fluid) with a nuclear powered water pump that constantly pumps the water in a circle. This loop is slowly lowered near the event horizon of a black hole, let's even make it a super duper massive black hole to minimize tidal effects...
  39. L

    How Fast Can Water Flow from a Kitchen Faucet on the Third Floor?

    Homework Statement water in main pipe at the street level is at a gauge pressure of 170 KPa and is moving with neglibible speed. A pipe connected to the main pipe is used to deliver the water to kitchen located on the third floor of a building, at a 15-m height from the street level. what is...
  40. F

    Fluid Mechanics HW How pressure in a tank affects exit velocity of a fluid

    I'm just a bit lost on how to find the change in pressure. I've posted a picture of my work thus far.
  41. Egregious

    Simple question about fluid pressure (medical injection)

    Hello, and thank you kindly for considering my question. Background: Medical needles come in gauges such that a smaller gauge represents a larger needle. Scenario: Doctor Jack says "18 gauge needles are best for this procedure", but Doctor Jane says "27 gauge needles are best because...
  42. K

    Fluid Mechanics Viscosity Question

    Homework Statement Hi guys, I'm pretty new here, and long story short, I'm struggling a bit on a fluid mechanics question I've been doing for some revision. A shaft 70 mm in diameter is being pushed at a speed of 400 mm/s through a bearing sleeve 70.2 mm in diameter and 250 mm long...
  43. N

    What is the pressure at the bottom of the flask?

    Homework Statement Liquid 1 (density ρ_{1} = 8290 kg/m³) is poured into a large open cylinder to a depth of d_{1} = 85.9 cm. Liquid 2 (density ρ_{2} = 5695 kg/m³) is then poured on top of liquid 1 to a depth of d_{2} = 70.3 cm. Then liquid 3 (density ρ_{3} = 2933 kg/m³) is poured on top of...
  44. Z

    Fluid mechanics: calc the acceleration of a particle at a point.

    Homework Statement A velocity field is given by \vec{V}= [Ax^{3} + Bxy^{2}]\hat{i} + [Ay^{3} + Bx^{2}y]\hat{j}; A=0.2 m^{-2}s^{-1}, B is a constant, and the coordinates are measured in meters. Determine the value and units for B if this velocity field is to represent an incompressible flow...
  45. D

    Fixed Mass of Viscous/Inviscid , Compressible/Incompressible Fluid

    Hello there , could you please explain to me what would happen to an inviscid/viscous incompressible flow (energy,momentum and entropy wise)falling from a height ? ( i.e a dam ) Thanks;)
  46. U

    Fluid mechanics water tank level

    Homework Statement A large cylindrical tank has a hole of area A at its bottom. Water is poured in the tank by a tube of equal cross-sectional area A ejecting water at the speed v a)The water level in the tank will keep on rising. b)No water can be stored in the tank. c)The water level...
  47. T

    One way fluid valve- no moving parts

    I am trying to come up with a shape or design of a simple piston with holes that will allow fluid to flow in one direction better than the other. Very Simple shock design. I have tried tapered holes so as to speed up flow in one direction and it worked slightly but haven't quite found the...
  48. U

    Fluid mechanics of floating wood

    Homework Statement A piece of wood is floating in water kept in a bottle. The bottle is connected to an air pump. Neglect the compressibility of water. When more air is pushed into the bottle from the pump, the piece of wood will float with a)larger part in the water b)lesser part in the...
  49. I

    Calculating volume flow rate per unit width of a plate ( Fluid Mechanics )

    This is the question The flow of a fluid between two large flat parallel plates normal to the y direction is fully developed and steady. The plates are a distance 2h apart in the y direction and the velocity profile, assuming y=0 is at the midpoint between the plate is V(y) = V_0(1-(y/h)^2)...
  50. A

    What Determines the Maximum Height for Water Flow in a Faucet?

    The main water enters a house on the first floor. the line has a gauge pressure of 1.9x10^5Pa a) A faucet on the second floor 6.50 meters above the first floor is turned off. what is the gauge pressure of this faucet? b)how high could a faucet be before no water would flow from it even if the...
Back
Top