Challenge

Week 8 - Simulation of a backward facing step in OpenFOAM

AAbhijith K Menon24 Nov 2021

Incompressible flow:

In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric flow) refers to a flow in which the material density is constant within a fluid parcel—an infinitesimal volume that moves with the flow velocity.

Laminar Flow:

In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another

The two main types of laminar flow hoods are horizontal and vertical. Horizontal laminar flow hoods pull air from the environment; the air goes through a filter and then blows smoothly out the front of the hood back into the room.

Viscous Flow:

A viscous flow is one where shear deformations of fluid elements is present and presence of nearby boundaries is observed through a resistance property of fluid called viscosity.Every fluid is viscous but whether viscous effect will show up or not, it depends upon on surrounding boundaries of flow as wall of channel in flow makes viscous effects appear

PROCEDURE:

1. By opening openfoam we follow the below code in "run" folder .This is how the pattern goes

Tutorials ---> Incompressible---->Icofoam------>cavity

2. Here we copy cavity folder into a new folder named "cavity_test"

3. After that cavit------>system------->blockmesh files and editing works as mentioned in the question

Blockdict File:

In blockdict file we create and name vertices according to the given sketch in the question by dividing into blocks. In this case there are 21 vertices and 5 blocks.

below shown are the calculated vertices for this case:

(fig 1)

Then in the blockdict file itself we need to specify number of mesh points along x,y,z directions and simple grading must be done along the boundries.

first simulation:

(fig 2)

blocks
(
    hex (0 1 2 3 11 12 13 14) (50 10 1) simpleGrading(0.2 5 1)
    hex (3 2 4 5 14 13 15 16) (50 10 1) simpleGrading(0.2 0.2 1)
    hex (2 7 6 4 13 18 17 16) (50 10 1) simpleGrading(5 0.2 1)
    hex (1 8 7 2 12 19 18 13) (50 10 1) simpleGrading(5 5 1)
    hex (10 9 8 1 21 20 19 12) (50 10 1) simpleGrading(5 5 1)

);