Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150641

150641 - Turbulent Rayleigh-Bénard Convection of Jovian Planets’ Gases in a Cylindrical Enclosure: The Effect of Bulk Temperature 

The atmospheres of astronomical bodies consist of layers of gases and aerosols held in place by gravity. Aerosols are tiny particles suspended in a gas that serve as cloud condensation nuclei for cloud formation in astronomical bodies. The atmosphere of Earth majorly consists of nitrogen and oxygen gases, with water vapor condensing on aerosols to form water clouds. The gas giants of our solar system—Jupiter, Saturn, Uranus, and Neptune—are known as the Jovian planets. These planets' atmospheres are made up of hydrogen and helium gases with ammonia clouds (Jupiter and Saturn) and methane clouds (Uranus and Pluto).

Rayleigh-Bénard Convection (RBC) is an idealized model of thermally driven convection that occurs when a planar horizontal layer of fluid is heated from below and cooled from above, resulting in temperature gradients. The temperature gradients give rise to fluid motion, which is influenced by buoyancy forces. RBC is encountered in a variety of engineering systems, as well as geophysical and astrophysical phenomena, and it is the major natural phenomenon by which clouds are formed on planets. Understanding the interactions among aerosols, cloud droplets, ice crystals, and trace gases within planetary atmospheres is crucial for advancing our knowledge of celestial bodies.

The novel Planetary Cloud Aerosols Research Facility (PCARF), developed by NASA Jet Propulsion Laboratory (JPL), is meant to provide an experimental resource that complements current and future research toward increasing our understanding of the planetary atmosphere and cloud formation. The facility aims to create controlled environments to investigate specific mechanisms under controlled conditions, ensuring repeatability with known initial/boundary conditions rather than simulating full cloud process complexity.

In this numerical study, computational fluid dynamics (CFD) analysis is performed to understand the effect of bulk temperature variation on RBC cell formation in a model of the PCARF cloud chamber to help guide its design. This study’s hypothesis centers on the fluid’s behavior having turbulent patterns and characteristics exhibited for each case of bulk temperature.

To investigate the effect of varying the bulk temperature on the formation of turbulent RBC phenomena, ANSYS commercial software is used for the CFD analysis to numerically solve the governing and transport equations and discretize them using the ANSYS Fluent “CFD code.” The PCARF cloud chamber model—a 9.42 m³ cylindrical enclosure made of stainless steel—is used for this study. Hydrogen (H2) and Helium (He) gas mixtures—the major Jovian planets’ gases—serve as the working fluids for this study, with bulk temperatures of 150 K, 200 K, and 250 K.

Preliminary results reveal the impact of the choice of bulk temperature, meshing, and boundary/initial conditions on the Rayleigh number, turbulent patterns, and dynamics of the Rayleigh-Bénard convection of the working fluids. These findings serve as a basis to enhance our understanding of aerosol-cloud formation in planetary atmospheres, contributing to the broader field of planetary science. 

Presenting Author: Ebenezer Ashimolowo Southern University and A&M College

Presenting Author Biography: Ebenezer is a Graduate Research Assistant at the Department of Mechanical Engineering of Southern University and A&M College. As a research assistant in thermal and fluid science, Ebenezer utilizes his expertise in Computational Fluid Dynamics in his graduate research to solve real-world problems.
He has a proven track record of proactive work attitude, extensive experience in leadership, research, decision-making, engineering simulation, modeling, and design software, and collaboration skills in diverse team environments to solve complex engineering problems

Authors:

Ebenezer Ashimolowo Southern University and A&M College
Stephen Akwaboa Southern University and A&M College
Patrick Mensah Southern University and A&M College