REU NSF FURI/WAESO

FURI Abstract for spring 2011:

This project continued the investigations from previous semesters on the sensitivity of Earth's climate through rotating tank experiments. The fluid motion in the rotating tank emulates global atmospheric circulation produced under two controlled parameters: the rotation rate of the planet and pole-to-equator temperature gradient. In this semester, new experiments were performed with an added outer cylinder that greatly enhanced the control on temperature gradient. Their outcome will be used to discuss the variation of the climate state due to a perturbation in the temperature gradient. A prrliminary set of complementary numerical simulations using ANSYS-FLUENT will be discussed.

A Classroom model for understanding Earth’s Climate Change

I have been working with Dr.Huei-Ping in rotating fluid experiments to further our understanding in abrupt climate change for our third semester under FURI’s generous support. I have taken the initiative to expose the research at a national conference in Washington D.C known as the “Emerging Researchers National Conference (ERN-Conference)” to better prepare for graduate school as I would hope to do a PhD in computational fluid dynamics modeling. Our Grand Challenge is Sustainability and we emphasize technology and engineering. In the school of Mechanical, Aerospace, Chemical, and Materials Engineering we continuously strive to improve our rotational device through a series of scaled-down fluid experiments for understanding climate change. By using a scaled-down fluid system of Earth we are able to view just how sensitive Earth’s climate system actually is by looking at two key parameters such as rotation rate and the temperature gradient contrast. Being able to view the phenomenon of the flow patterns as they emerge within the tank brings a sense of appreciation for our Earth-science and how this science serves as the driving force in our climate system.

In this semester, we have begun to design a new rotational fluid experiment for enhancing the radial control of the temperature within the tank. In last semester we designed, created, implemented, and successfully obtained our Rossby waves (large jet streams) results for emulating the atmosphere. Similarly, this semester’s new design should be able to portray the heat transfer through the convection of the fluid flow inside the tank. The purpose of modeling the heat transfer in the tank is to visualize the “heat spots” in the Earth. The purpose of running the experiment is because differential heating pertains to have similar properties in continental regions such as North America and Asia. We will use this technique of modeling heat transfer through the tank by heating a boiled pot of water to around 30 degrees Fahrenheit with contrasted 0 degrees Fahrenheit and room temperature 20 degrees Fahrenheit. We will visualize these results by using a thermal infrared camera from borrowed from an ASU Professor, Dr. Phelan. The casting of the experiment will lead to further insight in the area of fluid dynamics.

Furthermore, with the research I have begun to use the tools of Computational fluid dynamics (CFD) solver ANSYS-FLUENT to

validate our fluid experiments. The case of validating the experiments is ongoing. I have set up the geometry using ANSYS-Workbench and

created the mesh of the geometry in Workbench. I have also set some initial and boundary conditions (thermal loads) in Fluent and run the model in

Fluent to obtain preliminary velocity and temperature profiles in the tank.

Overall, the pole-to-equator temperature gradient has much influence on the sensitivity of our climate system. Our research has shown that

a modest perturbation can dictate the behavior of the fluid flow whether it be slight variations in temperature or rotation. By being able to

explore new experiments within fluid dynamics our understanding of climate change will bring us much insight further down the road along the lines

of global warming/cooling.

Reference:

Illari, L., and coauthors, 2009, “Weather in a tank: Exploring laboratory experiments in the teaching of meteorology, oceanography, and climate", Bull. Am. Meteor. Soc., vol. 90, 1620-1632

Further steps have included the attempt to cross validate the laboratory experiments with numerical simulations using the computational fluid dynamical solver in ANSYS-Fluent. One picture can be seen here as a preliminary model for validating the lab experiments:

Here posted are Rossby waves video that was accomplished successfully from last semester, Fall 2010 experiment.

http://www.youtube.com/watch?v=Zo-BHSR-lVo

What we have simulated in the lab thus far:

Here, we are preparing the tank for simulation of the global atmosphere.

Here is the begining stage of the zonal flow taking place in the rotating tank with no pertrusion.

A three wave structure pattern can be viewed here . One can appreciate the beauty of water flow simulated in a rotating tank that correlates

to our atmosphere.

Heat (or diffusion) equation:

∂u/ ∂t = ∂2u/∂ x2 ,

describes the diffusion of temperature or the

density of a chemical constituent from an initially concentrated distribution (e.g., a "hot spot" on a metal

rod, or a speck of pollutant in the open air)

Linear advection equation: ∂u/∂t = c ∂u/∂ x , describes the constant movement of an initial

distribution of u with a "speed" of - c along the x-axis. The distribution moves while preserving its shape.

These are Rossby waves.

They are large waves that occur in our atmosphere.

Reference from: http://en.wikipedia.org/wiki/Rossby_wave,

Rossby parameter

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The Rossby parameter (or simply beta β) is a number used in geophysics and meteorology which arises due to the meridional variation of the Coriolis force caused by the spherical shape of the Earth. It is important in the generation of Rossby waves.

The Rossby parameter β is given by the equation:

[1][2]

Where φ is the latitude, ω is the angular speed of the Earth's rotation, and a is the mean radius of the Earth.

Although both involve Coriolis effects, the Rossby parameter describes the variation of the effects with latitude (hence the latitudinal derivative), and should not be confused with the Rossby number.

Videos-Rotational fluid experiments for understanding/emulating climate change:

Here posted the relevant 9 videos regarding the lab experiments done for Spring 2011 Semester:

http://www.youtube.com/my_videos?feature=mhum