Let's get FLUENT (training session at BITS Pilani)

Let’s get FLUENTSession 1

Aniket Tekawade

Philosophybehind CFD

… My take on it

Enter the Matrix

“the universe is a Computational

Grid or a MATRIX

”

Imagine our world simulated by a code…

… and the man who knew the bugs in the code (Neo).

The underlying idea:

… the man who wrote the code (the Architect)

…

So what’s withCFD &

The Matrix?

CFD is about making your world a computational grid…

… and predicting the flow of fluids in it

Does CFD Completethe Matrix?

NO!!

Not everything in the world “flows”

But we are just making a humble attempt…

…at completing it

Just like in the movie, the bugs make the world

“unreal”…

…in CFD, the wrong set of

equations makes it “unreal”

The ‘code’ thatdefines CFD

Every element in the grid is a

“finite volume”

… and the flow equations are

solved over the FV

The flow equationsContinuity Balance

Momentum Balance(Navier Stokes)

Heat Transfer

Species Balance

Etc..

Each equation is solved on one cell

(FV) in a sequential manner……data obtained on one

cell is used to calculate data on the next, solving

again the same equations……the first cell

uses the BC/IC as initial values to

start with.

End result is a grid full of values (v, P, T, etc.) for each cell

…for your viewing pleasure ;-)

How to read what you see

… the idea of flow fields

…taken from www.bakker.org

…each cell stores data of velocity vector

…note that flow occurs around the dino

…pressure is higher in stagnated regions (bernoulli theorem)

Colorful pictures aren’t enough…

We need numbers...

Setting up yourown problem

•Create the appropriate domain…•Create your computational grid…•Select the right physical models…•Define your flow materials…•Prescribe operating conditions…•Describe boundary conditions…•Give an initial solution (initialize)…•Choose solver controls…•Set monitors and the run!

Take a look back…(Validating your solution)

…is your “matrix” real enough?

•Has your solution converged?•Are your values in the right scale/range?•Is your y+ in the right range? (later)•Are your species reacting realistically?•Does your benchmark problem match with calculations?

Thank you