CFD Analysis ProcessThereare few main components of CFD design cycle.
Below are the following importantsteps: 1. ProblemstatementFirst, states the problem to be solved and identifythe flow problems. Notice the physical phenomenon need to be considered in thisanalysis. Besides, create the geometry of the object (domain) and thosenecessary operating conditions. After that, notice the internal obstacles,internal-surface and free surface of the object.
Identify the type of flowwhether it’s laminar, turbulent or it’s a steady or unsteady flow. 2. MathematicalmodelFirst, a proper flow model, good viewpoint andreference frame are chosen. Identify the forces that influence the fluidmotion. Second, problem is set with the computational domain. Writes out allthe related formula for the conservation law of mass, momentum and energy.Furthermore, equation is simplified for reducing the computational effort.
Lastly, specify those necessary boundary conditions. 3. DiscretizationmethodFirst, Partial differential equations system (PDE) istransformed into a set of algebraic equations.
Through this, it is createdbecome approximately, become discretized versions and because of those smallpart element. It became more easily to be solved. In fact, there are many waysto discretize the partial equations but in the end. The goal of all the methodsare the same, that is turn a calculus problem that human cannot solve into analgebra problem which human can solve. Below is some example of discretizing method:· Discretization of spatialvolumes through finite difference, finite element and finite volume.· Discretization of gridtopology through structured, unstructured cartesian and generalizedunstructured. 4. CFDSimulationFirst, once the object in 2D geometry such asrepresentative cross section is created.
It is necessary tofamiliar those parameters in the simulation.Once simulate it, there are something that can obtained from this simulation.For example, investigation of effect of fluid properties on the overall object,what proper meshing and what appropriate boundary layer meshing to be used andestimate the accuracy that expected from a 3D model. Furthermore, the qualityof simulation results based on some few factors such as assumptions made beforethe simulation, mathematical model and quality, size of mesh and so on. 5. PostprocessingAfter CFD Simulation, the next step is to extract theimportant information from the computed flow field.
The important informationsuch as the calculation of derived quantities and integral parameters,verification of CFD model and visualization of 1D, 2D and 3D value. 6. Errorand uncertaintyResults of CFD simulation is depends on theaccumulation of error and the level of variability. The source of causinguncertainty is might be not enough of knowledge about CFD. Error might be causeby other reasons. If comparing both of it. Error is more easily to find out compareto uncertainty. This is because, error have many ways to determine, estimatingand solving them.
But for uncertainty, there is no proper way to find it outbecause it is because of lack of knowledge about CFD. So, it might remain theproblem that undiscovered ever and in the end. It might also cause otherdifferent big problems. (Patel, 2013) Advantages of CFDAgain,Computational Fluid Dynamics (CFD) is a software or can be said as system topredict the fluid flow, heat transfer, mass transfer, chemical reaction and soon. Furthermore, there are a lot of benefits about it.
First, development cost.It is very expensive that using real or physical experiments and tests to getsome important engineering data for design purpose. Thus, this software is usedto get those important data and it is relatively inexpensive in cost. Data getfrom CFD sometime is more accurate as it is using computer to calculate.
Second, execution time. CFD simulation can run or so call test in a shortperiod of time, this make engineering data introduced early before the designprocess. Third, overall data. Experiments or tests can only get those data inlimited location and it is not so detailed, but CFD allows to get more precisedata and it is very comprehensive. Lastly, simulation under many conditions. Inreal experiment, some fluid flow or heat transfer process cannot be easilycontrol or tested under different kind of conditions. But in CFD, it providesthis ability.
Disadvantages of CFDEventhough there are a lot of advantages about CFD. However, there are also havedisadvantages of it. First, for an CFD investor, they have no power to vote orsay in an engineering company since CFD is not their underlying asset. Second,for CFD system, it is very hard to get a perfect grid for a complex geometry,sometimes it can but very time consuming. Besides, it is also very difficult toget the accurate flow motion result over the whole thing in simulation.
This isbecause, those data required a good quality in grid session, perfect grid isvery hard to get for a complex geometry. Lastly, this system is not so friendlyto all people and it is quite complicated to be used as well. Thus, it has totake a long time to keep one practice in how to use this software and how toanalyse the results. Application of CFD ComputationalFluid dynamic can be used in many ways for predicting the important data todesign something. Below are some examples of application of CFD:· Smoke control system· Classroom· Swimming pool ventilation· Aerospace· Automotive· Electronic Infact, there are still a lot of application about CFD but not necessary to showall of it.
Smoke control system is one of the most common usage of CFDapplication. CFD has the capability to simulate the smoke flow in a space withcomplex geometry. This idea is keeping the smoke away from the objects or to besaid as occupants for saving their life when accident happens. From here showsthat, why CFD is so important in simulation before designing the building forsafety issues. (Saeidi, 1998) Figure 2 Figure3 Figure2 shows the smoke away from the building when accident happens. Figure 3 showsit’s result of simulation in CFD.