Fluid Definition and 1000 Threads

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. N

    Fluid Mechanics: Friction of a moving surface

    Hey! So for Newtonian fluids, the shear-stress is given by \tau = \mu \frac{du}{dy} Now, let's assume you have water flowing horizontally in laminar steady state motion, where its surface is also moving. Above it is air. So if we disregard the friction from air, the shear-stress will become...
  2. M

    How much math for fluid dynamics?

    hey all im taking a graduate level fluid mechanics course. we are using a good amount of vector calculus (expected) and also tensor algebra, leading into the kronecker delta and Levi-Civita symbol (shockingly never saw these before, though implicitly used them). it seems linear algebra is...
  3. S

    Introductory Fluid Mechanics book.

    Could someone recommend me a good Introductory Fluid Mechanics book? It's only an introductory course so it doesn't have to be too comprehensive at all. Thanks.
  4. N

    Steady state in fluid mechanics

    Hey! When a stream is steady-state, you can cancel the acceleration term in navier-stokes equation, right? so: \rho \vec{a} = 0 = - \nabla P + \rho \vec{g} + \mu \nabla ^2 \vec{V} But there are many terms in the total acceleration which are not dependant on time! The acceleration term in...
  5. K

    Water Vortex Power Plant: Fluid Resistance

    Hi, I would like some help for my final project. I'm trying to find an eqn for fluid resistance which is present on the frontal side of the blade as it spins: so far what I've come up by dimensional analysis is the drag force equation: F=Cd x ( ρ x v^2)/2 x A to get the fluid...
  6. B

    Engineering Researchers in fluid mechanics: engineers , Physicists ?

    Researchers in fluid mechanics: "engineers", "Physicists" ? Dear all, I was reading the book "Turbulent flows" of S. Pope and I went to his website at Cornell and started to see his work. In case you do not know him, I can tell you that his work is 100% applied mathematics and fluid physics...
  7. T

    Fluid mechanics and circular flow

    Dear all I am having a problem on circular flow of fluid. On all books I have read they say \frac{dp}{dr}=\rhov^{2}/r Which make sense by using infinitesimal square volume and take the force exert. But if I use a circular infinitesimal volume (which is usually the case for circular...
  8. F

    Fluid pressure question in US units

    Homework Statement The ocean liner Titanic lies under 12500 feet of water at the bottom of the Atlantic Ocean. (The density of water is 62.4 lb/ft{}^3.) What is the water pressure at the Titanic? (Give your answer in both pounds per square foot and pounds per square inch.) Homework...
  9. Z

    How Do You Calculate Airflow and Pressure Changes in a Duct System?

    fluid mechanics question help!? Homework Statement Air flows through a horizontal duct of dimensions 300 x 300 mm with a velocity of 15 m/s. At position (1) in the duct a water gauge (water manometer) registers a hieght of 215mm. The duct bends downwards and reduces in size to 240 x 240 mm...
  10. G

    How Do You Determine Pipeline Pressure with a Faulty Manometer?

    Homework Statement You are given an open-ended mercury manometer and asked to determine the pressure in a pipeline that supplies feed gas to a reactor. However, when you connect the manometer to the pipeline, you notice that the calibration markings in the leg that connects to the...
  11. W

    Discover the Proof for the Dynamic Viscosity Formula in Fluid Mechanics

    What is the prove for this formula, or in another way the provement of the dynamic viscosity multiplied by the shear strain will get us the shear stress,
  12. M

    Can someone please check my homework on fluid dynamics?

    Hi there, I just would like if someone could check over my work on my current homework assignment involving fluid dynamics. Homework Statement 1) Calculate the absolute pressure at an ocean depth of two kilometers. Assume the density of seawater is 1000 kg/m3, the density of air is 1.3...
  13. M

    Fluid flowing in a sphere and leaving

    Homework Statement Homework Equations The Attempt at a Solution Just checking if this is correct, and if the equation in part c implies that the flow rate out changes with time, or is just based off the initial height..I think it changes and therefore requires this integration. Also, I looked...
  14. D

    Rate of flow, or velocity of fluid?

    I was looking at a site which described the classic demonstration to illustrate how water pressure increases with depth (shown by punching three holes, one above the other separated by a few centimeters, in a container of water): "The smaller the holes, the greater the rate of flow from the...
  15. D

    Can you 'increase pressure' by restricting fluid flow?

    I just read this, from a site dedicated to popularizing science: " ...think of air as being like water. If you have a garden hose and put your thumb over the end, the pressure increases and water sprays out. Same thing with air. Except the increased pressure is under a plane's wings and...
  16. Z

    Fluid Mechanics shear stress, conceptual question

    Homework Statement Consider a fluid between two plates. One on the bottom which is stationary, and one at the top which is moving at constant velocity V. The plates are separated by distance h. Does shear stress change as you move further from the moving plate? Homework Equations the...
  17. B

    Shear Stress and Fluid Mechanics

    Homework Statement It's a relatively simple problem I'm sure, but I'm a bit confused on how exactly to go about it: There are three parallel plates with water (viscosity of 0.8807 cp @ 30°C) between plates 1 and 2 (plate order of 1 on bottom, 2 in middle, 3 on top), and toluene (viscosity...
  18. C

    Viscous fluid flow in a manufacturing process

    In work that I've been doing, we've come across an interesting problem. In a manufacturing process, a highly viscous, non-Newtonian fluid goes down a vertical chute and then gets pushed horizontally out the bottom by some rotating screws. Sometimes, the fluid gets pushed out the bottom, but...
  19. O

    DE word problem: fluid in a tank

    Homework Statement Consider a tank used in certain hydrodynamic experiments. After one experiment the tank contains 200 L of a dye solution with a concentration of 1 g/L. To prepare for the next experiment, the tank is to be rinsed with fresh water flowing in at a rate of 2 L / min. The...
  20. F

    Fluid flow - pressure v volume?

    This a practical problem for the design of a system which uses a water driven hydraulic motor. Assume a 100 gallon tank is filled with water, constantly filled further pressurized by a pump to 500psi Assume a hydraulic powered motor which operates with intake required at 200psi...
  21. F

    Controlling fluid Flow under pressure?

    this is not a homework problem, its a practical problem for a system I'm working on, but its looks pretty much like a homework problem so posting here. Homework Statement Assume a 100 gallon tank is filled with water, constantly filled and pressurized by a pump to 1000psi Assume a hydraulic...
  22. zhangwfjh

    On representation of expansion in fluid flow

    In Helmholtz original thesis On integrals of the hydrodynamical equations, which express vortex-motion, he mentioned in the first section that the change undergone by an arbitrary infinitesimal volume of water under the time dt is composed of three different motions. One of them is an expansion...
  23. R

    Calculating Pressure Change in a Manometer Due to Removal of Air Bubble

    Homework Statement a manometer consisting of tube that is 1.25 cm inner diameter . on one side , the manometer leg contains mercury,10cc of an oil(S.G.=1.4)and 3 cc of air as a bubble in oil . the other leg contains only mercury . both legs are open to atmosphere and static . An accident...
  24. D

    Pressure, energy density, and power of a fluid flow

    I've read that you can view static pressure of a fluid as energy density, which makes sense to me. I've also seen that the power of a fluid flow can be calculated by multiplying the pressure by the volumetric flow rate. However, doesn't a flow also have kinetic energy? How can you calculate the...
  25. B

    Fluid mechanics problem, need explanation please

    Hi please check the highlighted question in the attachment and the solution and see the problem, i need help please. I have two questions about it: 1- why didn't we take the plug as a vertical wall and thus the force would be integral of pressure x area? 2-WHERE DID THE FORCE DUE TO...
  26. B

    Simple Fluid mechanics question, Need Help

    I've been solving fluid mechanics problems and i encountered two problems that made no sense to me. Both problems that ask about the force done by water on a VERTICAL wall under the level of water. One problem was solved by taking the integral of the gauge pressure and multiplying it by the...
  27. N

    Lagrange-Young equation in Fluid Mechanics

    Young-Laplace equation in Fluid Mechanics EDIT: I meant the Young-Laplace equation, of course, not the Young-Lagrange.. sorry! Heya! According to said equation, ΔP*area = γ*circumference, for an interface of spherical fluid-element. Can I pls get some explanations? 1) Why is...
  28. M

    Fluid Dynamics - Calculate the resultant moment

    Homework Statement A rigid vertical wall separates two liquid reservoirs. The first reservoir contains oil of density p=864 kgm-3 at a height of 6m above the ground, while the second reservoir contains water (1000kgm-3) at a height of 5m from the reservoir bottom. Calculate the resultant...
  29. A

    Fluid mechanics book recommendation for new grad

    Hey all, I'm a Math major (most of my coursework was in PDEs) and just got accepted into Grad school (yay) for Mechanical Engineering. I need to be very familiar with fluid mechanics and have about 5 months to do so. Trouble is, the last fluid mechanics course I took was about 3-4 years ago...
  30. C

    Determining the viscosity of a fluid

    Homework Statement Two flat plates are oriented parallel above a fixed lower plate as shown below, The top plate, located a distance b above the fixed plate, is pulled along with speed V. The other thin plate is located a distance 0.3b (cb) above the fixed plate. This plate moves with speed...
  31. M

    Rising fluid between conducting cylinders

    Homework Statement Two long, hollow, and coaxial conducting cylinders, with radii a and b>a , are lowered into a tub of fluid with dielectric constant \kappa . A voltage V is applied between the two cylinders. The fluid is observed to rise up some height h into the volume between the...
  32. Z

    'Expansion' of fluid world lines

    hello In MTW excercise 22.6, given a fluid 4-velocity u, why the expression : ∇.u is called an expansion of the fluid world lines ? Is the following reasoning correct ? We know that the commutator : ∇BA - ∇AB is (see MTW box 9.2) is the failure of the quadrilateral formed by the vectors...
  33. M

    Velocity and mass relation by fluid jet propulsion of a squid

    Several species, including the squid, cuttlefish, dragonfly fish and many microscopic organisms, move themselves around by a kind of jet propulsion. In each case the animal absorbs fluid in a body cavity and expels it through an orifice by contracting the cavity. If a squid has a mass Ms when its...
  34. R

    Fluid Flow Problem-Viscous Flow

    I am working on a fluid mechanics problem modeling something I've come into contact with at work. I have an open to atmosphere reservoir of a fluid with properties as follows SG=1.48 Viscosity= 47000 Cp Height of fluid column, 3 inches or so. i.e. Neglible I then have a pressure...
  35. M

    Recursive model for body in fluid

    Good evening, I've been trying to wrap my head around this problem for some time and I just can't seem to get it straight. What I am trying to achieve: I want to program a recursive model that calculates the position of a moving body in a fluid after a certain time. What i have done...
  36. B

    How can the probability of a particle entering a fluid flow be modeled

    Ok so maybe this will take some work to wrap your heads around. Maybe not. I sure know that I have had some real doozies of headaches working with this and visualizing it. Rather than look at particle capture in a gold sluice as a CFD problem I have been trying to visualize it as a statistcal...
  37. Tclack

    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...
  38. W

    Fluid Mechanics Newtons law of viscosity

    Homework Statement having problems differentiating Homework Equations Tw ( wall shear stress)= -U(viscosity)*du/dr been given u as 2V(1-(r/r)^2) The Attempt at a Solution i substituted u in and got d/dr (2V(1-(r/r)^2) i tried to multiply out the minus sign and 2V and got...
  39. V

    How Can Two Stones and a Stopwatch Help Measure the Width of a Lake?

    Homework Statement The question asked is: Two students are given 2 stones and a waterproof stopwatch, along with swimwear. Using this material they are then required to estimate the distance across a lake. This question could obviously be answered using fairly simple process, however, it is...
  40. liometopum

    Fluid mechanics, source-sink question

    In fluid mechanics, the velocity of the liquid going in or out (source-sink) of a hole in a two dimensional model is Q/(2 pi r). http://farside.ph.utexas.edu/teaching/336L/Fluidhtml/node63.html What is the velocity in three dimensions? Is it Q/(4 pi r^2) ?
  41. M

    Fluid Mechanics - Resistance to fluid motion using Chezy's formula

    Homework Statement The quantity of water delivered through a buried pipe line that is 2 000 m long and has an inside diameter of 200 mm has over the years steadily decreased to 80 % of its original flow. This is due to encrustation inside the pipe. It was then decided to have the pipe...
  42. M

    Fluid Dynamics–Find pipe diameter,head loss & actual mean velocity.

    1. Homework Statement a) Calculate the theoretical diameter of pipe, nominal pipe diameter and mean velocity of nominal pipe diameter. Maximum velocity = 1.8m/s Q(vol. flow rate) = 0.01M^3-1 b) Find the Reynolds number for the process and then the head loss due to friction, state any...
  43. G

    Thought experiment about fluid compressibility

    I'm a physics noob but this is something I was thinking about when I read in my textbook that fluids are generally incompressible. Let's say I had 1000 L of water enclosed in a sphere several meters thick (say, 2 meters thick) made of an extremely hard, dense metal with 0 outlets or holes of...
  44. T

    Why does fluid flow faster in a narrow tube?

    Fluid flows faster in a narrow tube which results in low pressure and high pressure in a large tube?
  45. P

    Incompressible fluid acquiring momentum

    Suppose we have the set up shown in the thumbnail, in which an incompressible fluid moves from left to right, trapped by converging streamlines. The rate of acquisition, F, of momentum by the fluid is surely F = \rho A_2 v_2^2 - \rho A_1 v_1^2 = \rho A_1 v_1^2 \left\{\frac{A_1}{A_2} -...
  46. K

    Question Fluid Mechanics(Robert Granger) fluid Velocity comp.

    Question "Fluid Mechanics(Robert Granger)" fluid Velocity comp. Chapter 4. eq. 4.28- 4.30 u = u0 + (x - x0)(du/dx) + (y - y0)(du/dy) + (z - z0)(du/dz) v= ... w = ... Then without any significance explanation these equation take a form of eq 4.31 - 4.33 u = u0 + 1/2...
  47. M

    Time to achieve specific heat transfer for fluid flowing in a pipe

    I am currently in the process of designing a section of pipe in which a fluid will flow within, and would like to determine the specific heat transfer which may occur once the fluid enters the pipe, until it exits. The fluid will be flowing at a constant velocity "V" at a Temperature "T1" at...
  48. G

    Does decreasing pressure of fluid in a fixed volume lower temperature?

    Sorry if the formulation is imprecise, I'm a biology major trying to study some physics. The question is: So far, my reasoning is: I make an assumption in Step (2) that decreasing the pressure will decrease the temperature. But I'm not sure what the justification is. I only know of the ideal...
  49. T

    Velocity of a fluid within a pipe

    Homework Statement A scientist attempts to model the flow of blood through an artery using a hollow pipe of diameter 1.8cm. A fluid density 1060kg/m^3 is used to simulate blood in the pipe. Viscous effects can be considered to be negligible. TO study a blockage in an artery, the...
  50. Q

    Relativity with Charged Particles & Fluid Approx.

    Hello community, I'm new here. I'm using FORTRAN to model the motion of electrons and ions when accelerated under a high voltage potential. I'm using a fluid approximation and MHD-like equations (conservation of mass, energy, momentum) and a finite volumes numerical method to solve the...
Back
Top