Indirect Natural Convection

This project focused on the numerical study of near-wall dynamics in indirect natural convection, with an emphasis on understanding flow structures, heat transfer, and the effects of throughflow. The work involved computational fluid dynamics (CFD) simulations to analyze the behavior of plume structures and their scaling with the Rayleigh number (Ra) for fluids with Prandtl numbers (Pr) of 0.7 (air) and 5.2 (water).

Key Objectives:

1. To investigate the scaling relationships between plume spacing, plume length, and heat flux with the Rayleigh number.

2. To study the near-wall flow structures in indirect natural convection.

3. To examine the effects of throughflow (transverse velocity) on convection dynamics.

   
   

Methodology :

• CFD Simulations: Conducted using ANSYS Fluent CFD software to model Rayleigh-Bénard convection with the Boussinesq approximation for density variations.

• Image Processing: Used MATLAB to analyze plume structures and measure plume lengths

• Fortran-Based Model: Developed to study the impact of throughflow on plume spacing and heat transfer.

  
  

Key Findings :

• Plume Dynamics: Near-wall flow structures were observed as line plumes, with plume length increasing and spacing decreasing with the Rayleigh number.

• Heat Transfer: The Nusselt number (Nu) scaled as Nu ∼ C Ra^n, where n = 0.26 for air and n = 0.3 for water, indicating near-wall dominance in heat transfer.

• Throughflow Effects: Throughflow reduced heat flux and decreased dimensionless plume spacing, with numerical results aligning well with theoretical predictions.

  
  

Significance:

• The study provided insights into near-wall dynamics and heat transfer in indirect natural convection, which are relevant for applications in atmospheric boundary layers, oceanography, and engineering systems.

• The numerical results were validated against experimental data, demonstrating the accuracy of the computational approach.

• The investigation of throughflow effects offered a deeper understanding of how transverse velocities influence convection, which can help control instability in natural convection systems.

  
  

This project contributed to the understanding of plume dynamics, heat transfer scaling, and the impact of throughflow in indirect natural convection, offering valuable insights for both theoretical and practical applications.

Tools used : Ansys Fluent, Ansys ICEM CFD, Fortran, Matlab, Tecplot

Publication : ASME Journal of Heat Transfer

Gallery :

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