Week 1- Mixing Tee

Aim: For this challenge, we have created two versions of the mixing tee. One of them is longer than the other.

Your job is to set up steady-state simulations to compare the mixing effectiveness when hot inlet temperature is 36⁰C & the Cold inlet is at 19⁰C.

Use the k-epsilon and k-omega SST model for the first case and based on your judgment use the more suitable model for further cases. Giving the reason for choosing a suitable model is compulsory.

1. Case 1
• Short mixing tee with a hot inlet velocity of 3m/s.
• Momentum ratio of 2, 4.
2. Case 2
• Long mixing tee with a hot inlet velocity of 3m/s.
• Momentum ratio of 2, 4.

Momentum ratio = velocity at cold inlet / velocity at hot inlet

In a table, compare the following values from the 2 cases.

1. Cell count
2. Average outlet temperature
3. Number of iterations for convergence

Reference Formulas:-

Tmixture = mh*Th+mc*Tc/mh+mc

Procedure:

1. Step one import the model in Spaceclaim and trim the edges using Volume Extract command after that surpress the solid.

2. After that import the model mesh module and provide name selection to different face after that generate mesh.

3. Next step is import model in setup and provide boundaries condition to model and generate iteration as per requirement.

4. Last step is to import the Model in CFD fluent and study the result of the respectively.

What is mixing tee?

Mixing tee is basically used for mixing two different flow streams to form the gradients of the combined flow streams

Case 1.1 short tee

hot inlet temp = 36 C

Cold inlet temp = 19 C

Momentum = 2

hot inlet velocity = 3 m/s

cold inlet velocity = 6 m/s

In Case 1.1 we study for k-epsilon and k-omega SST

Geometry setup

Mesh Generation

Boundaries condition y-inlet,x-inlet,output,wall.

Setup and Solution

Setup	k-epsilon	k-omega SST
Velocity	Absolute	Absolute
Time	Steady	Steady
Viscous-model	k-epsilon,Realizable,standard	k-omega,SST model
Material	Air	Air
Cell Zones	Fluid type: Air	Fluid type: Air
Boundaries	Momemtum: 2 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 6 m/s cold inlet temp: 19C Output: pressure outlet wall:stationery walls	Momemtum: 2 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 6 m/s cold inlet temp: 19C Output: pressure outlet wall:stationery walls
Iteration	Hybrid	Hybrid

k-epsilon model:

Residual Plot:

Area-Weighted Average of temp:

Standard Deviation:

Velocity-Area-Weighted Average of Velocity-Magnitude:

Temperature Contour:

Velocity Contour:

k-omega model:

Residual Plot:

Area-Weighted Average:

Standard Deviation:

Velocity: Area-Weighted Average:

Temperature Contour:

Velocity Contour:

Case 1.2 Short tee

hot inlet temp = 36 C

Cold inlet temp = 19 C

Momentum = 4

hot inlet velocity = 3 m/s

cold inlet velocity = 12 m/s

In Case 1.2 we study for k-epsilon and k-omega SST

Setup and Solution

Setup	k-epsilon	k-omega SST
Velocity	Absolute	Absolute
Time	Steady	Steady
Viscous-model	k-epsilon,Realizable,standard	k-omega,SST model
Material	Air	Air
Cell Zones	Fluid type: Air	Fluid type: Air
Boundaries	Momemtum: 4 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 12 m/s cold inlet temp: 19 C Output: pressure outlet wall:stationery walls	Momemtum: 4 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 12 m/s cold inlet temp: 19 C Output: pressure outlet wall:stationery walls
Iteration	Hybrid	Hybrid

k-epsilon model:

Residual Plot:

Area-Weighted Average:

Standard Deviation:

Velocity: Area-Weighted Average:

Velocity Contour:

k-omega model:

Residual Plot:

Area-Weighted Average:

Standard Deviation:

Velocity: Area-Weighted Average:

Temperature Contour:

Velocity Contour:

Numerical Solution: Momemtum = 2

Area of hot inlet = 0.00091 m

Area of cold inlet = 0.00025 m

Velocity at hot inlet = 3 m/s

Velocity at cold inlet = 6 m/s

Temperature at hot inlet Th = 36 C

Temperature at cold inlet Tc = 19 C

Density of air (rho) = 1.29 kg/m^3

Mass of hot air mh = rho*A*V=1.29*1000*0.00091*3= 3.5 kg

Mass of cold air mc = rho*A*V=1.29*1000*0.00022*6= 1.7 kg

Tmixture = mh*Th+mc*Tc/mh+mc= 3.5*309+1.7*292/3.5+1.7 = 303.44 K = 30.44 C

Momemtum = 4

Velocity at hot inlet = 3 m/s

Velocity at cold inlet = 12 m/s

Temperature at hot inlet Th = 36 C

Temperature at cold inlet Tc = 19 C

Density of air (rho) = 1.29 kg/m^3

Mass of hot air mh = rho*A*V=1.29*1000*0.00091*3= 3.5 kg

Mass of cold air mc = rho*A*V=1.29*1000*0.00022*12= 3.4 kg

Tmixture = mh*Th+mc*Tc/mh+mc= 3.5*309+3.4*292/3.5+3.4 = 300.62 K = 27.62 C

Case 1.3 Long tee

hot inlet temp = 36 C

Cold inlet temp = 19 C

Momentum = 2

hot inlet velocity = 3 m/s

cold inlet velocity = 6 m/s

In Case 1.3 we study for k-epsilon and k-omega SST

Geometry setup

Mesh Generation:

Setup and Solution

Setup	k-epsilon	k-omega SST
Velocity	Absolute	Absolute
Time	Steady	Steady
Viscous-model	k-epsilon,Realizable,standard	k-omega,SST model
Material	Air	Air
Cell Zones	Fluid type: Air	Fluid type: Air
Boundaries	Momemtum: 2 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 6 m/s cold inlet temp: 19C Output: pressure outlet wall:stationery walls	Momemtum: 2 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 6 m/s cold inlet temp: 19C Output: pressure outlet wall:stationery walls
Iteration	Hybrid	Hybrid

k-epsilon model:

Residual Plot:

Area-Weighted Average:

Standard Deviation:

Velocity: Area-Weighted Average:

Temperature Contour:

Velocity Contour:

k-omega model:

Residual Plot:

Area-Weighted Average:

Standard Deviation:

Velocity: Area-Weighted Average:

Temperature Contour:

Velocity Contour:

Case 1.4 Long tee

hot inlet temp = 36 C

Cold inlet temp = 19 C

Momentum = 4

hot inlet velocity = 3 m/s

cold inlet velocity = 12 m/s

In Case 1.4 we study for k-epsilon and k-omega SST

Setup and Solution

Setup	k-epsilon	k-omega SST
Velocity	Absolute	Absolute
Time	Steady	Steady
Viscous-model	k-epsilon,Realizable,standard	k-omega,SST model
Material	Air	Air
Cell Zones	Fluid type: Air	Fluid type: Air
Boundaries	Momemtum: 4 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 12 m/s cold inlet temp: 19 C Output: pressure outlet wall:stationery walls	Momemtum: 4 x-inlet velocity: 3m/s inlet hot temp: 36 C y-inlet velocity: 12 m/s cold inlet temp: 19 C Output: pressure outlet wall:stationery walls
Iteration	Hybrid	Hybrid

k-epsilon model:

Residual Plot:

Area-Weighted Averagee:

Standard Deviation:

Velocity: Area-Weighted Average:

Temperature Contour:

Velocity Contour:

k-omega model:

Residual Plot:

Area-Weighted Average:

Standard Deviation:

Velocity: Area-Weighted Average:

Temperature Contour:

Velocity Contour:

In this table,compare the following values from the cases

	Short tee	M = 2	M = 4	Long tee	M = 2	M = 4
Cell Count	3758			5111
Average Temperature		303.44 K	300.62 K		303.44 K	300.62 K
No of Iteration		400	150		400	150

Conclusion:

1. We sucessfully Mesh the short tee as well as long tee.

2. We successfully solve all the iteration of short tee as well as long tee.

3. We sucessfully plot the temperature and velocity contour of short tee as well as long tee.