What is Flow control: Definition and 13 Discussions

In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an imperative programming language from a declarative programming language.
Within an imperative programming language, a control flow statement is a statement that results in a choice being made as to which of two or more paths to follow. For non-strict functional languages, functions and language constructs exist to achieve the same result, but they are usually not termed control flow statements.
A set of statements is in turn generally structured as a block, which in addition to grouping, also defines a lexical scope.
Interrupts and signals are low-level mechanisms that can alter the flow of control in a way similar to a subroutine, but usually occur as a response to some external stimulus or event (that can occur asynchronously), rather than execution of an in-line control flow statement.
At the level of machine language or assembly language, control flow instructions usually work by altering the program counter. For some central processing units (CPUs), the only control flow instructions available are conditional or unconditional branch instructions, also termed jumps.

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  1. tracker890 Source h

    Question about source flow rate across line AB.

    Q:Please hlep me to understand which ans is correct.To determine the flow rate in Line AB. $$\mathrm{Known}:V_A,q,r_A = constant.$$ so/ select:## A,{B}^{\text{'}},B,A,## is control volume $${Q}_{AB}={Q}_{A{B}^{\text{'}}}=\iint _{A}^{}({V}_{A})dA={\int }_{{\theta }_{A}}^{{\theta...
  2. M

    Getting an exact amount of Methane out of a cylinder

    Hello, I am currently working on a research project that involves filling a 10L tedlar bag with about* 8 liters of methane gas from a compressed gas cylinder. I'm trying to work out the best way to fill the bag with a reasonable degree of accuracy while also minimizing (or hopefully avoiding...
  3. B

    HVAC High Flow Control with High Pressure and Temperatures

    Hello all, I am currently building a test bench that can input a high amount of flow, pressure and temperature into an Air Cycle machine. The inlet to the machine requirements are: Flow = 71 lbs/min P = 48 PSIa T = 235 degree F Diameter = 3 inches In order to produce these conditions, I have...
  4. M

    What is the difference between nozzle (or a ventury) and flow control valve?

    In both the cases, the flow cross section area of the pipe is reduced.But in case of nozzles the velocity increases,pressure reduces and the flow rate is maintained.But in case of flow control valve, flow rate changes.(Assuming the fluid to be incompressible) Why is there a difference between...
  5. A

    What is the Best Control System for Compressed Air in a Drone?

    Hey, I'm working on a project to build a drone which is powered through air jets. The drone needs a valve control system which can control the flow rate (hence the thrust) going to each nozzle in order to adjust it's altitude and stabilty. I need to set up a circuit which can electronically...
  6. T

    I How Can Boundary Layer Suction Reduce Flow Separation in Pipe Expansion?

    I have a question about the following scenario involving a flow separation issue in a pipe expansion The angle of the expansion is 30* - doubling the diameter from 1D to 2D We can consider this flow fully developed with a Reynolds of 5000+ Associated with this expansion is a head loss...
  7. S

    What is the flow through pipe in an open channel?

    I know this is easy but i need to know the flow velocity through a pipe reducing in diameter inside a canal. the water velocity is 3m/s water depth is 1.5 m the pipe is at the bottom inlet diameter 0.9m small reduced diameter 0.6m outlet diameter = 0.8m note: this is an open canal with...
  8. campblor

    Thermodynamics flow control?

    I have this problem and have been pulling what's left of my hair out: The Wivenhoe hydroelectric power station requires water to be pumped from Wivenhoe Dam to Splityard Creek Dam, using two pumps (each consuming 250 MW of power at 98% efficiency) to elevate the water approximately 70 m. At...
  9. F

    Understanding the Flow Control Principle of Valves

    How exactly would you describe the principle of a valve for flow control? In a globe valve for example the fluid flows through valve seat and generally leaves the valve with the outlet diameter being the same as the inlet diameter. My original assumptions were that Bernoulli's principle...
  10. J

    Research Labs for Flow Control - RPI & Maryland

    Does anyone know of any good university labs that do research in flow control and its many applications? I know RPI has a flow control lab and Maryland does some research in this as well.
  11. E

    Mass flow control and ideal gas calculation

    Homework Statement I have an experimental setup consisting of a 755ml stainless steel cylinder being fed with Hydrogen from atmospheric unitl 10 bar. I am using a Brooks Mass flow controller to measure and control the flow of Hydrogen into the cylinder while at the same time recording the flow...
  12. V

    Flow Control Valves - Help for Mech Engg Student

    hello i am a mech engg student, i have few doubts in fluid dynamics and thermal engg subjects.. i would like to be cleared of them by this discussion forums could anyone please explain the principle of flow control using valves...waiting for ...
  13. J

    Energy Flow Control Systems

    Relevant question An energy flow control system is one where electrical signals are used to control the flow of energy. quite often electrical energy. A modern example of one such system is the manual control of the speed of a sewing machine motor by way of a foot opearated variable...