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. M

    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...
  2. C

    SG (Specific Gravity) in Fluid

    Homework Statement [/B] When asked for the bouancy of a hollow cylinder, containing air, submerged in ocean water. outer radius R. Length of cylinder = L The Material of the cylinder is neglected. I'm thinking the Bouancy (Force) = ρ ⋅ g ⋅ v where v = LπR^2 and therefore F = ρgLπR^2 But the...
  3. T

    Lowest Kinematic Viscosity Fluid - High Pressure Gas

    I am trying to determine which fluid to use in an experiment. An important aspect of the experiment is the ratio of inertial forces (due to mass) vs the viscous forces that the fluid will experience Amongst common liquids the lowest I can see is Acetone with a kinematic viscosity of 0.41 cSt...
  4. Alfreds9

    Water evaporation, temperature, wind and heat capacity?

    Hi, I'd like to know how I'd put together, either elegantly or at least in physical terms, that surely water evaporation in a large pool of V volume and S surface is influenced by wind (increased by it as opposed to having side barriers), temperature (increased by direct sunlight as opposed to...
  5. G

    Engineering Fundamentals of Fluid Dynamics

    I'm looking for a book to really help hit home what my fluids class is teaching because I'd like to eventually learn the Navier Stokes Equation. Syllabus: 1. Introduction, definitions, fluid kinematics 2. Hydrostatics, including nanometers, Bourdon gauges and pressure transducers 3. Control...
  6. S

    Solve question using Excel or Matlab

    water moves over a stationary horizontal flat plate of one-meter length. if velocity of water is 1 m/s, draw boundary layer and friction coefficient versus x for this plate. hint: start your curves from x=1cm.Professor asked us to do it in Matlab or Excel and I'm not sure I understand how to...
  7. Villa

    In fluid mechanics what does pressure energy mean?

    In Bernoulli equation we use pressure energy... Pressure* volume gives the unit of energy... But what does this mean... If someone says it is potential energy per unit volume, then what does datum head refers to?... Please help... Can't go ahead without having thorough knowledge about this..
  8. D

    Fluid speed in a straight pipe

    Hello everyone I have a simple question regarding how to calculate the speed of a fluid in a normal pipe with a constant cross-section If we are given the pressure difference at the two ends of the pipe (P1 and P2) is it possible to calculate the speed of the fluid? (I think I can imagine this...
  9. G

    High-pressure compression of liquids

    Hello, My memories of fluid mechanics are very rusty and therefore I was wondering if you could help me with this hypothetical problem. Let's say I want to generate very high hydrostatic pressures in a liquid (of order of 400 kbar). Would it be enough to do the following: take a rod weighting 1...
  10. J

    Is there a difference between redirection and converging flow in fluid dynamics?

    Fluid or sleeve bearings use an off center shaft location to generate a hydrodynamic wedge in direction of rotation. This converging fluid causes higher pressure and can support a load applied normal to shaft axis during rotation. This action appears to be similar to the hydrodynamic support of...
  11. S

    Plotting pressure distribution of fluid flow in a pipe

    Hi all, I am analysing the flow of water in a subsea pipe, and have been getting stuck in trying to solve the energy equation to plot a temperature distribution across the pipe diameter I have derived the equation as such seen in my attachement. But my main question is how should/would I...
  12. B

    Force exerted by a agitated fluid on vessel wall

    How can I calculate the pressure exerted by a fluid on the walls of the vessel that is being agitated. The vessel is not pressurised. I have to calculate the resultant pressure on the walls to calculate the thickness of the vessel walls.
  13. S

    MHB Combination of field and particle methods for fluid dynamics

    hello, in numerical fluid dynamics there are field methods like finite-volume, finite-element, etc. and particle methods like Smoothed-Particle-Hydrodynamics – SPH and others. Both approaches have advantages and disadvantages depending on the application. Both, in principal completely different...
  14. thebosonbreaker

    I Non-Newtonian fluids at the quantum level

    I am intrigued by the diversity of Non-Newtonian fluids and need to ask a question. Can anyone provide me with a breakdown of what goes on at the quantum level as the Non-Newtonian fluid bounces up and down on top of the speaker in the video I have embedded. What I would like to know is...
  15. datf

    Solving Fluid Dynamics Questions: Pump Similarity Laws and Efficiency Comparison

    Hi guys, please help me with these questions. I've been racking my brain for days but I'm not sure of the answers. 1) (Assume that pump similarity laws are valid and that the effects of Reynolds number (Re) are small.) A centrifugal pump operating at speed N is combined in series with an...
  16. Mingsliced

    Fluid Mechanics - Head Loss Due to Friction

    Homework Statement This is simply a sanity check concerning the system described and attached. My concerns are detailed within my attempts at the solution. Any guidance will be greatly appreciated! The diagram attached represents a process for which a pump and associated pipe work require to...
  17. F

    Force of Reducer on Fluid Flowing Right

    Homework Statement is it correct to say that the force exerted by reducer on fluid directed to the left because of the fluid move from left to right ? Homework EquationsThe Attempt at a Solution
  18. UMath1

    I Is the Force Applied by an Object on a Fluid Equal to the Buoyant Force?

    If you place an solid object on a fluid, is the force it applies to the fluid equal to the buoyant force? I would have thought that it applies a force equal to its own weight but that would mean that the force applied to the object by the fluid, the buoyant force, would not be equal and opposite...
  19. S

    Fluid Flow Equations With Real Values

    Hi, all I am working on a project that involves analyzing fluid flow behavior in oil & gas pipelines. I am interested in calculating and plotting the velocity profile, and also(pressure distribution, temp distribution) Having studies fluid mechanics last year I am aware of the EOS for fluid...
  20. tomdodd4598

    Stokes Law/Drag Force corrections?

    Hi there, I have recently been experimenting with solid metal spheres being let to fall through fluids of different viscosities and have recently been introduced to the 'Ladenburg correction'. This correction multiplies the measured velocity of the sphere to obtain the 'correct' velocity used...
  21. L

    How to Determine Flow Rate in a Pipe Using Fluid Dynamics?

    Homework Statement http://imgur.com/DSBFIeO I want to find the flowrate through this pipe based on the pipe's diameter, height of the pipe and the pressure difference. I tried to use Bernoulli, but since the diameter on either end is the same, the terms cancel out. I guess Bernoulli's equation...
  22. C

    Stress tensor for non-Newtonian fluid

    How does one setup the stress tensor for a non-Newtonian fluid? I know that for any fluid the normals should be the pressure and for a power law fluid the shear stress in the direction of flow is related by K(du/dy)^n. Does this mean that all other components are 0 for a symmetric pipe or...
  23. W

    What is the formula for the weight of a fluid block?

    Homework Statement why the formula of weight of fluid block is given by the formula of ρg[ (R^2) - pi(R^2) ] 1? what does the 1m mean here ? shouldn't it = ρg (pi) (R^2) h ? 2. Homework Equations The Attempt at a Solution
  24. W

    Supporting Fluid: Reducing Shear Stress with Wall

    Homework Statement why the fluid need the wall to eliminate the shear stress? Homework EquationsThe Attempt at a Solution is it because if there is no wall to support teh fluid , the fluid would move continously , resulting the shear stress act on water?
  25. C

    Solve UROV Fluid Mechanics Homework: Max Vel, Time, Distance, Drag Force

    Homework Statement Im working with a UROV and I have a technical scenario that I am supposed to solve. It seems pretty easy but i keep getting ridiculous answers. Assuming a max thrust of 5 N for 1 motor/propeller, for the forward direction only, use the above information to determine the Max...
  26. KingDaniel

    Why should an ideal fluid be incompressible?

    Hi, I read that an ideal fluid needs to be frictionless and incompressible. Please explain why, especially the incompressible part? Thanks
  27. prashant singh

    What is the Best Book for Fluid Mechanics from Beginning to Advanced Level?

    which is better fluid mechanics book , frank white or munson from complete beginning to the advanced level.
  28. S

    Spring Oscillation in fluid

    So there is this ball held on a spring. It's radius R = 0.015m , and density ρ=7800kg/m^3. It's oscillation period in air is 1.256 seconds and in the fluid it changes to 1.57 seconds. Find the viscosity of the fluid considering that the drag force obeys Stokes law. I first found the spring...
  29. T

    Solving for Air Speed in an Air Duct

    Homework Statement A 15 cm. radius cylindrical air duct is used to replenish the air of a room 10 m.*6 m.* 3m. Every 10 minutes. Determine the speed of the air through the duct in m/s. A1=15 V1=? A2=19 V2=0 Homework Equations A1V1=A2V2 The Attempt at a Solution 3.14*15^2 * ?= 19*0=...
  30. sa1988

    Acceleration of fluid particle

    Homework Statement Find acceleration for a general point (x, y) at time t, in the velocity field u = (y, t-x) Homework Equations Du/Dt = ∂u/∂t + (u⋅∇)u The Attempt at a Solution ∂u/∂t = (0, 1) (u⋅∇)u = [(y, t-x)⋅(∂/∂x, ∂/∂y)](y, t-x) = (0 + 0)(y, t-x) = (0, 0) Thus Du/Dt = ∂u/∂t +...
  31. jdawg

    Fluid Mechanics:Volumetric flow rate and average velocity

    Homework Statement . Air, at a flow rate of 30 [N/s], flows through the reducer shown below. In the 300 [mm] diameter section of the pipe the specific weight of the air is 9.8 [N/m3 ]. When flowing through the reducer the pressure and temperature will fall causing the air to expand and...
  32. E

    Ball in accelerating tank with fluid

    T1. Homework Statement a wooden ball of mass m is kept inside water by the help of a massless string shown in the figure. One end of the string is fixed at the bottom of the vessel. when the vessel containing the water is accelerated upwards with acceleration a , will the tension increase and...
  33. sa1988

    Fluid dynamics, solving ODE to find particle path

    Homework Statement A time-dependent two-dimensional fluid flow is given, in a Cartesian coordinates system (x, y), by the velocity field: u = (y, t-x) Show that, at time t = 0, the streamlines of this flow are circles centred on the origin. Find equation of the streamline that passes through...
  34. C

    Fluid Mechanics Videos: Resource for Video Lectures

    Hello, does anyone know a good resource for video lectures on the subject of fluid mechanics?
  35. S

    Fluid Dynamics - Pressure at the end of a syringe

    Hello there Physics Forum! This is my first post here. This problem has been boggling me all day and I'm need of help in piecing together what I've come up with so far. I'm currently working on a personal project related to paint spraying. In this project I'm using a syringe & needle to feed...
  36. jdawg

    Fluid Mechanics: Cart and tank of water

    Homework Statement A cart has a tank of water on it which has a nozzle. Water jets out from the nozzle onto a turn vane oriented at theta = 30° which deflects the flow upward. The cart is held stationary by a rope as shown in the image below. Find the force in the rope if the velocity of the...
  37. jdawg

    Fluid Mechanics Velocity at Outlet

    Homework Statement Water flows through a 1.5 [in] diameter pipe. In a 1.5 [ft] section of the pipe water is injected through the porous walls into the pipe at a velocity of 3 [in/s]. What is the average velocity at the exit if the inlet velocity is 6 [ft/s]? Homework EquationsThe Attempt at a...
  38. M

    Calculating Pipe Diameter for Desired Pressure in Inclined Fluid Flow

    The question: There is a 650m long tube on a 1 degree incline. At one end of the tube is a pump that alone has a volumetric flow rate of 750 g/min. The fluid in question is water and its a PVC pipe. What diameter does this tube need to be in order to have 25 psi on the top end of the tube...
  39. M

    Nontoxic, high transmittance, high density fluid

    Hi, I'm looking for a liquid that is nontoxic, high transmittance, has a specific gravity higher than 1.3. Here is the catch. I'm using it to separate resin, so it can not dissolve or react with resin. there was a similar topic on high density fluid on other forums, but I'm using it...
  40. CivilSigma

    Separation of Particles in a fluid flow?

    Hello, I'm doing some online research on fluid flow in waste water treatment. One of the problem I'm trying to find information about is how can visible particulate matter be separated within a liquid. I saw the following picture: What fluid concepts are going here that allow the grit to...
  41. jdawg

    Fluid Mechanics Gate Problem

    Homework Statement A rectangular plate AB is 1.8 [m] wide and 2.0 [m] long. As shown below the plate is used to keep water (blue region) confined to the region. Find the weight of the gate necessary to keep the water enclosed. Assume the hinge at A is frictionless. Homework EquationsThe...
  42. kartmaze

    Fluid Velocity from a Pipe onto an Inclined Plane

    I'm not really sure where to post this. I saw that this Homework section exists even for technically non-homework (I'm designing a machine at work, but the problem is homework-esque and my fluid dynamics knowledge is rusty at best). I'm not sure if this introductory or advanced, and the template...
  43. C

    Ideal fluid flow velocities & pressure

    1. Air at 0∘C flows through the tube shown in the figure. Assume that air is an ideal fluid. What is the air speed v1 at point 1?2. Formulas: A1V1=A2V2, ΔP + 1/2ρΔV2, ρgΔh3. My first through process was to calculate the change in pressure in the mercury as the change in pressure in the...
  44. H

    Rotation in a cylindrical cylinder (fluid)

    Homework Statement what's the difference between zs and hc ? in the pictuire , they are both drawn from the bottom of water to the free surface ... Homework EquationsThe Attempt at a Solution [/B]
  45. T

    How is it that fluid velocity increases by a low pressure

    So I've always thought that an increase in velocity of a fluid would decrease pressure. However, I've heard the opposite and that it is an decrease in pressure that increases velocity. All I want to know which one is correct (in terms of something like a venturi pipe) because an decreasing...
  46. G

    Total energy of the flowing fluid

    Homework Statement Since this scanned notes is not clear enough , so I retype some parts of the notes, The enthalphy , h is given by the formula , h = u +Pv = u + P/ ρI want to ask about the total energy of the flowing fluid , which is given by the formula = P/ ρ + e = h + ke +pe = h + (V^2)...
  47. S

    States of Matter That Aren't Fluids

    Aside from solids, are any of the known states of matter (exotic or otherwise) considered to not be fluids? As a side note, I'd like to appologize in advance if this turns out to be posted under the wrong category of physics, I could not tell which category this would fall under and this seemed...
  48. A

    Conceptual question, fluid pressure in a barometer

    Homework Statement I took a stab at the following question in a book: "In one observation, the column in a mercury barometer has a measured height h of 740.35 mm.The tem- perature is -5.0 C, at which temperature the density of mercury r is 1.3608 10^4 kg/m^3 .The free-fall acceleration g at...
  49. A

    Work done by gravity on fluid in u-tube.

    Homework Statement Two cylinders of base area 4cm2 hold fluid of density 1.30(103). In one the fluid has height .854 and the other has height 1.560. They are then joined and the fluids equalize in height--find the work done by gravity on the fluid. Homework Equations A version of...
  50. A

    Why Does the Shape of a Container Not Affect Fluid Pressure Calculations?

    for static fluids we have studied that p=patm +density*g*depth. and this equation is derived from Newton's laws,but in fbd why didn't we consider the force exerted by curved surface area of container,it doesn't cancel out when containers are in frustrum shape.and the vertical components add up...
Back
Top