Week 1- Mixing Tee

AIM:

Solve the mixing of hot and cold fluid diffusion for a given problem using work bench and fluent under steady-state simulations and compare the mixing effectiveness when hot inlet temperature is 36°C & the Cold inlet is at 19°C. Use the k-omega SST model for all cases.

Case 1: Short mixing tee with a hot inlet velocity of 3 m/s and Momentum ratio of 2 & 4.

Case 2: Long mixing tee with a hot inlet velocity of 3 m/s and Momentum ratio of 2 & 4.

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

• Cell count
• Average outlet temperature (Theoretical & Numerical)
• Number of iterations for convergence

FORMULA USED:

Momentum Ratio =Velocity at cold inlet / Velocity at hot inlet

PROCEDURE:

• There are two cases for the given model.
• Case 1:
  1. Short mixing tee with a hot inlet velocity of 3 m/s.
  2. Momentum ratio of 2 & 4.
• Case 2:
  1. Long mixing tee with a hot inlet velocity of 3 m/s.
  2. Momentum ratio of 2 & 4.

Short Mixing Tee with Momentum Ratio of 2

• First we import the short tee model in the new space clam geometry.
• Then extract the geometry.
• Then suppresed for Physics.

• Then we go for meshing and generate the mesh for the given model with element size 2mm.
• we got number of elements 106253
• We use laminar flow model.

• Then we name the model
  • Inlet X
  • Inlet Y
  • Outlet
  • Wall body
• Then we go to setup and set the simulation
• Set the hot inlet velocity 3m/s and hot inlet temperature is 36°C.
• Then by formula Momentum Ratio = Velocity at cold inlet / Velocity at hot inlet, Cold inlet velocity = 6m/s and cold inlet temperature is 19⁰C.
• 172 iteration to model is coverge
• So we got outlet temperature is 30.405331°C
• And velocity at outlet is 4.505545 m/s

RESIDUAL PLOT FOR SHORT TEE WITH MR=2

TEMPERATURE PLOT FOR ST WITH MR=2

STANDARD DEVIATION TEMPERATURE PLOT FOR ST WITH MR=2

TEMP CONTOURS

PRESSURE CONTOURS

VELOCITY CONTOURS

• Then we go to post processing i.e, result for this model.

Temperature variation

Velocity Saparation

TEMP. PLOT

VELOCITY PLOT

SHORT MIXING TEE WITH MOMENTUM RATIO = 4

• Then by formula Momentum Ratio = Velocity at cold inlet / Velocity at hot inlet, Cold inlet velocity = 12m/s and cold inlet temperature is 19⁰C.
• So we got outlet temperature is 27.5482°C.
• And velocity at outlet is 6.0643581 m/s.

RESIDUAL PLOT FOR SHORT TEE WITH MR=4

TEMPERATURE PLOT FOR ST WITH MR=4

STANDARD DEVIATION TEMPERATURE PLOT FOR ST WITH MR=4

TEMP CONTOURS

Pressure Contours

Velocity Contours

Results

Temperature Variation

Velocity Variation

Temp. Plot

Velocity Plot

LONG MIXING TEE WITH MOMENTUM RATIO = 2

• First we import the short tee model in the new space clam geometry.
• Then extract the geometry.
• Then suppresed for Physics.

• Then we go for meshing and generate the mesh for the given model with element size 2mm.
• we got number of elements 140942
• We use laminar flow model.

• Then we name the model
  • Inlet X
  • Inlet Y
  • Outlet
  • Wall body
• Then we go to setup and set the simulation.
• Set the hot inlet velocity 3m/s and hot inlet temperature is 36°C.
• Then by formula Momentum Ratio = Velocity at cold inlet / Velocity at hot inlet, Cold inlet velocity = 6m/s and cold inlet temperature is 19⁰C.
• 117 iteration to model is coverge.
• So we got outlet temperature is 30.430177°C.
• And velocity at outlet is 4.4980804 m/s.

RESIDUAL PLOT FOR LONG TEE WITH MR=2

TEMPERATURE PLOT FOR LT WITH MR=2

STANDARD DEVIATION TEMPERATURE PLOT FOR LT WITH MR=2

TEMPERATURE CONTOURS

PRESSURE CONTOURS

VELOCITY CONTOURS

RESULTS

TEMPERATURE VARIATION

Velocity Variation

Temp. Plot

Velocity Plot

LONG MIXING TEE WITH MOMENTUM RATIO = 4

• Set the hot inlet velocity 3m/s and hot inlet temperature is 36°C.
• Then by formula Momentum Ratio = Velocity at cold inlet / Velocity at hot inlet, Cold inlet velocity = 12m/s and cold inlet temperature is 19⁰C.
• So we got outlet temperature is 27.585447°C
• And velocity at outlet is 6.0160007 m/s

RESIDUAL PLOT FOR LONG TEE WITH MR=4

TEMPERATURE PLOT FOR LT WITH MR=4

STANDARD DEVIATION TEMPERATURE PLOT FOR LT WITH MR=4

TEMPERATURE CONTOURS

PRESSURE CONTOURS

VELOCITY CONTOURS

RESULTS

TEMPERATURE VARIATION

Velocity Variation

Temp. Plot

Velocity Plot

Cases	Temperature at Outlet	SD Temperature at Outlet	Velocity at Outlet
Short Tee with MR=2	30.405331°C	1.8918452°C	4.505545 m/s
Short Tee with MR=4	27.5482°C	1.2502364°C	6.0643581 m/s
Long Tee with MR=2	30.430177°C	1.179265°C	4.4980804 m/s
Long Tee with MR=4	27.585447°C	1.0076544°C	6.0160007 m/s