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.

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  1. M

    A Sessile drop fluid oscillations and frequencies

    Hi PF! I'm looking at a sessile drop of water in ambient air. The drop is plucked lightly, inducing surface oscillations. The fundamental frequencies ##\lambda_i## can be computed from spectral theory, and output complex values, say ##\lambda_1 = 2+7i##. Now, I simulate the experiment via CFD...
  2. jahan123

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  3. C

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  4. Kaushik

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    Look at the above figure. An overhead view of a car passing a truck on a highway. Air passing between the vehicles flows in a narrower channel and must increase its speed. As the speed of air in that narrow channel increases, the pressure reduces (between the two vehicles). What is the reason...
  5. T

    Fluid passing through a convergent-divergent nozzle

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  6. ValeForce46

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  7. E

    I Pressure vs Normal Stress: Exploring Bird Transport Phenomena

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  8. ValeForce46

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  9. B

    Use of ammonia as the OTEC working fluid

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  10. M

    Fluid Oscillating in a Channel CFD

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  11. F

    I Why in the steady flow of a fluid, the fluid cannot move through the wall....?

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  12. M

    Fluid Interface Frequency Transform

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  13. Bortei

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  14. V

    Basic fluid mechanics questions about an oceanography paper

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  15. K

    Fluid dynamics and sound waves

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  16. M

    Fluid Mechanics problem: Oil pressure calculations in pipe flow

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  17. saxman2u

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  18. nn2e19

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  19. L

    I Optimal Copper Pipe Size for Misting System

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  20. Clout

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  21. A

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  22. T

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  23. M

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  24. M

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  25. J

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  26. M

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  27. WhiteWolf98

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  28. WhiteWolf98

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  29. M

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  30. B

    I Analytical Open Channel Rectangular Fluid Flow

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  31. A

    Velocity gradient decomposition of a fluid flow

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  32. A

    Fluid Mechanics, Particle Size, Bouyouncy Force

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  33. W

    HVAC Understanding the movement of a fluid in a vertical pipe

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  34. X

    Would acceleration under water affect the person?

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  35. P

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  36. LordGfcd

    A fluid mechanics problem -- Shape of a falling water drop

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  37. rumborak

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    I'm doing a fun home project, and it involves water flowing through a metal pipe, where the surrounding is significantly lower temperature than the water in the pipe. The point of the exercise is to cool the water in the pipe as it flows through it. The question is, what influence does flow...
  38. NatanijelVasic

    I Subsonic and Supersonic Airflow Through a Constriction

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  39. CharlieCW

    Conductor sphere floating on a dielectric fluid

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  40. Alexanddros81

    I want to understand this equation - Fluid Mechanics

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  41. WhiteWolf98

    Fluid Mechanics: Determining Elevation in a Piezometric Tube

    Homework Statement [/B] Homework Equations ##P=\rho gh## The Attempt at a Solution So this is the first time I'm doing fluid mechanics, and I'm trying my best to understand it. This was the first question, and truth to be told, I'm not very confident. I know what gauge pressure is: the...
  42. C

    I Trying to better understand what viscosity really is

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  43. G

    I Pascal's law (fluids): Derivable from fundamental laws?

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  44. T

    Determining ceramic particle sizes suspended in a fluid

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The density of the material was 3800 kg m–3 and the density and viscosity of the fluid at room temperature were...
  45. I

    Measuring Pressure For Compressible Fluid Systems?

    Is measuring pressure for a compressible fluid system angle dependent?For a compressible fluid, Bernoulli's Law gives us a relation between two points along a closed system. More specifically it gives us the relation between two cross sections belonging to two distinct points in the closed...
  46. M

    What does the word 'Jet' mean in fluid mechanics?

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  47. T

    Energy equation for fluid mechanics

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  48. F

    Pressure inside the zeppelin for it to float

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  49. S

    B How can I model a density function of a compressible fluid?

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  50. K

    I Why is the Energy Momentum Tensor of a Perfect Fluid a Tenso

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