Week 1: Channel flow simulation using CONVERGE CFD

AIM:- Channel flow simulation using CONVERGE CFD

 

OBJECTIVE

1. For this challenge, we will be setting up a channel flow tutorial.

2. As you watch these videos, set up the case in CONVERGE

3. Make sure the inlet pressure and initial pressure are the same. 

4. Once you have the base setup ready, run the case for three different base mesh sizes

i.e You need to run 3 simulations and compare the results between all the 3 simulations.

3 different base mesh sizes are,

•  dx = 2e-4m,              dy = 2e-4m,       dz = 2e-4m
•  dx = 1.5e-4m,           dy = 1.5e-4m,    dz = 1.5e-4m
•  dx =  1.0e-4m,          dy = 1.0e-4m,    dz = 1.0e-4m (If this is too much for your PC, use 1.2e-4m)

 

Contents to be shown in the report:

1. Velocity and pressure contours for all the 3 base mesh sizes

2. Show mesh (i.e surface with edges) for the 3 base mesh sizes

3. Plots for velocity, pressure, mass flow rate, and total cell count for all 3 base mesh sizes.

4. Explain the plots and write a detailed report on your project.

5. Upload an animation to youtube and attach the link here using the add media option. Explain the development of the flow using the animation.

Make sure you make your project public. Once you are done, paste the link to your project here.

 

INTRODUCTION:-

Channel flow is an internal flow in which the confining walls change the hydrodynamics structure of the flow from an arbitrary state at the channel inlet to a certain state at the outlet.

The simplest illustration of internal flow is a laminar flow in a circular tube while a turbulent flow in the rotor of a centrifugal compressor is an example of the most intricately shaped internal flow.

. Engineering devices complex channels with a cross-section of various geometrical shapes.

. In this project converge studio was used to establish a working idea of airflow simulation through a channel flow under certain parameters which will be elaborated on systematically in this report.

Theory:

Channel flow is an internal flow in which the confining walls change the hydrodynamic structure of the flow from an arbitrary state at the channel inlet to a certain state at the outlet.

 The simplest illustration of internal flow is a laminar flow in a circular tube (see poiseuille flow).

Poiseuille flow is pressure-induced flow (channel flow) in a long duct, usually a pipe.

It is distinguished from drug-induced flow such as counter flow.

Specifically, it is assumed that there is the laminar flow of an incompressible Newtonian fluid of viscosity $\mu$induced by a constant positive pressure difference or pressure drop Δp in a pipe of length L and radius R << L.

while fluid flow through the channel, the parabolic velocity profile is created.

Because the friction of the walls slows the fluid down. In fact, the velocity of the fluid at the wall is zero.

As you move away from the wall the velocity of the fluid increases until you reach the middle of the pipe, where it is at its max.

The resulting velocity profile is parabolic.

 

 

 

OBJECTIVE:-

1. Setting up a channel flow tutorial.

2. Velocity and pressure contours for all the 3 base mesh sizes

3. Show mesh (i.e surface with edges) for the 3 base mesh sizes

4.  Plots for velocity, pressure, mass flow rate, and total cell count for all 3 base mesh sizes.

5 .  Explain the plots and write a detailed report on your project.

6.  Upload an animation to youtube and attach the link here using the add media option. Explain the development of the flow using the animation.

 

 PROCEDURE:-

Create geometry:-

geometry:

here I have assumed the flow is poiseuille flow and i have taken the box-type channel. to run the simulation i have used converge software.

. I have created the above geometry in converge.

. To create the geometry, I have taken shape tool in geometry and then I selected the box tool in the shape tool.

. The dimensions of the box are length along the x-axis is 0.1m, along the y-axis is 0.01m and along the z-axis is 0.01m.

. The center of the box is 0.05m from the axis. 

. Now I have used the boundary tool in the geometry.  

. Here I have named the boundaries to the box.

. I have named the front and back 2D because I have taken the geometry to be 2D geometry.

. I am considering the 2D geometry because the channel length along the z-axis is infinite.

. So we can take any plane normal to the z-axis, and it shows the same results at every plane. I have taken xy plane

. Creating a geometry using the creation tool of Converge Studio

. Running diagnosis to check if there are any open edges or faces

. Checking the orientation of Normals, The normal should be such that their orientation is pointing towards the fluid flow.

 

 

ASSIGN TRINGLES TO SPECIFIED BOUNDARY 

The boundaries are flagged. The converge studio basically uses triangular blocks to create geometry. So by selecting the boundaries of the triangle are Flagged

Inlet

Outlet

Top and Bottom Walls

Front2D

Back2D

 

In the above figure, the sum represents the number of triangles selected at each boundary.

Now use the normal toggle tool.

In the converge, the normals are always directed to outside-of-the-box faces as a default.

but here the fluid is inward flow.

So eliminate them, click on the transform in geometry and select the triangle and click apply.

to check whether the geometry is correct or not(ie open edges errors, overlap errors), click on the diagnosis which is shown at the bottom left of the display, and click findings. mow build the case setup.

 

 

CASE SETUP: 

Application Type = Time-based

Materials- Air

click on gas simulation as the air is gaseous state and click on species to calculate how the mass fraction of N2 and O2 are changing along the flow.

Gas simulation is checked. The species are O2 and N2.

Simulation Parameter-

          In Run Parameters- two main things to be considered 

         (a). Select the following solver settings.

Steady-State Monitor:-

steady-state monitor-  It monitors the primitive variables and whether they reached the steady state or not.

The minimum number of cycles to be executed for a steady-state solver is 5000.

it tells us that even if we give the number of cycles to run the simulation at 15000, the software stop calculating the simulation if it reached the steady state between 5000 and 15000 cycles.

Monitor start delay indicates the simulation should run from zero cycles, that is from start.

simple size indicates the software takes the solution for every 1000 cycles and compares the difference in changing of primitive varisbles to see whether they reached a steady state or not. tolerance denotes the difference in changing primitive variables at every 1000 cycles. 

 . Simulation Parameter:-

Solver parameter [steady-state]

Navier -Stokes solver scheme:-

Equations:-

Steady-state solver control

Boundary Condition:-

1:- inflow

2:- Outflow

3:- Top-Bottom-Walls:-

Front 2D:-

Back 2D:-

Regions and initialization:-

 initial conditions and events:-

here I have named the entire box region as the volumetric region.

 

. Physical Models: Uncheck Turbulence Modeling in this Case:-

Grid Control:-

1:-Base Grid:-

Post-Varible Selection:-

output/post-processing:

Typical variable / Geometry:-

Combustion/Turbulence:-

 

Species/Passive:-