Air flow past stationary circular cylinder at moderate & high Reynolds numbers

Master's Project in collaboration with Pittsburgh Supercomputing Center

Project Guide: Dr. Anirban Jana

CMU Independent Study Paper:

- Desai, P. and Jana, A., Air flow past stationary circular cylinder at moderate and high Reynolds numbers, CMU Civil and Environmental Engineering, Independent Study, Aug, 2013

Flow past bluff body such as a circular cylinder is an important physical problem with many interesting theoretical aspects as well as practical applications. It is a problem which is easy to setup, both experimentally and computationally. Even though the setup is simple, the physics represented by this problem is quite complex and still remains a major research topic.

The basic physics of flow past a stationary cylinder is at the heart of myriad applications varying from the fields of streamlined design of cars to wind loading of high rise buildings to workings of musical instruments with strings. Another important application, for which research is currently ongoing at the Pittsburgh Supercomputing Center and University of Pittsburgh, is in the field of nuclear power: the high speed flow of hot coolant past the support posts in the lower plenum of Very High Temperature Reactor (Generation IV nuclear reactor) requires one to solve the problem of flow past a stationary circular cylinder. This application was the actual motivation behind the present study.

The focus of this study was the development of a computational model for the problem of air flow past a stationary circular cylinder. Reynolds numbers in the range of 40-150 (2D computational domain) were considered along with one case of Reynolds number as 3900 (3D computational domain). Physical quantities like time period of vortex shedding, base pressure coefficient, drag force and recirculation length for the 2D model were compared with published experimental and numerical results. A preliminary analysis was carried out for 3D model.

The open-source, finite-volume software OpenFOAM® was used in this study.

Study of air quality and thermal control efficiency inside commercial aircrafts: Airbus A380 and Boeing 747

Check out the section on "COVID-19-safe seats in intercontinental aircrafts"

Contributors: Nihar Sawant, Andrew Keene

Project guide: Dr. S. Singh

Airbus and Boeing are two of the biggest commercial aircraft manufacturers. A380-800 and 747-8 are the largest commercial aircrafts produced by Airbus and Boeing respectively. These aircrafts are typically used for intercontinental flights. All of us who have taken an intercontinental flight spanning over 8 hours are well aware of the thermal and air quality discomfort associated with these flights.

This study tries to answer: In an ideal world, if all the commercial aircraft seats of a particular class, viz. first, business and economy, were to be offered for a fixed price, is there a particular seat in each of these classes which has the best value for our buck? In this study, we perform a comprehensive computational analysis of a typical aircraft ventilation system (A380 and 747) to determine the seat where environmental factors are most conducive to human comfort with regards to air quality and thermal comfort levels. Air velocity, temperature and CO₂ concentration are considered for both Airbus and Boeing planes. In each plane the first class, business class and economy sections are analyzed. We present conclusions as to which is the optimum seat in each section of each plane and provide the data of the environmental conditions to support our inferences. Our 2D RANS computational model makes use of few assumptions like the placement of the inlets and geometry of the passengers and thus, is certainly not an absolute representation of the real aircraft.

ANSYS Fluent was used in this study.

Many factors are considered during the decision making process of purchasing a seat on a plane. Features such as costumer service, financial means, and inherent bias often drive the decision making process. However, these factors are not considered in our conclusions about the most-valued airplane seat. Furthermore, personal preference plays a significant role when choosing a seat. For example, a particular individual may prefer to sit by the window so they can see the view, or sit by the aisle so they can stretch their legs. Also the ideal environmental conditions used in the ranking scheme are an average and not the same for each individual. Some passengers may prefer a hotter ambient temperature and others, slightly cooler. For all these reasons, our findings should be used only as a tool to make a well-educated buying decision at one's own discretion.

Seat rankings for the economy section: