VMFL028

VMFL028
Turbulent Heat Transfer in a Pipe Expansion

Overview

Reference J.W. Baughn, B.E. Launder, M.A. Hoffman, R.K. Takahashi, “Local Heat Transfer Downstream of an Abrupt Expansion in a Circular Channel With Constant Wall Heat Flux”, Journal of Heat Transfer, Vol 106, pp. 789-796, 1984

Solver Ansys Fluent

Physics/Models Heat transfer, turbulent flow with recirculation and reattachment

Input File

bghnexp.cas

Project Files Link to Project Files Download Page

Test Case

Fully developed turbulent flow through an axisymmetric pipe expansion is modeled. The flow reattaches to the pipe wall downstream of the expansion, enclosing a zone of recirculation. The pipe wall downstream of the expansion is heated at a constant rate. Inlet to the computational domain is placed at 1 step height upstream of the expansion and the outlet at 40 step-heights downstream.

Figure 74: Flow Domain

Material Properties	Geometry	Boundary Conditions
Density: 1.225 kg/m³ Viscosity: 1.68318e-5kg/m-s Specific Heat: 1006.43 J/kg-K Thermal Conductivity: 0.0242 W/m-K	Pipe radius before expansion = 0.667 m Pipe radius after expansion = 1.6667 m	Inlet velocity: Specified by fully developed turbulent velocity profile Inlet temperature = 273 K Heat flux across the wall after expansion = 0.3 W/m²

Material Properties

Geometry

Boundary Conditions

Density: 1.225 kg/m³

Viscosity: 1.68318e-5kg/m-s

Specific Heat: 1006.43 J/kg-K

Thermal Conductivity: 0.0242 W/m-K

Pipe radius before expansion = 0.667 m

Pipe radius after expansion = 1.6667 m

Inlet velocity: Specified by fully developed turbulent velocity profile

Inlet temperature = 273 K

Heat flux across the wall after expansion = 0.3 W/m²

Analysis Assumptions and Modeling Notes

Steady flow in axisymmetric domain. The wall upstream of expansion is adiabatic.

Results Comparison for Ansys Fluent

Figure 75: Nusselts Number Variation along the Heated Wall