Mathematical Model for Convection Current

In summary, the conversation is about creating a mathematical model for a 2-D convection current in a cylindrical object with a heat source at the bottom. The person is struggling with finding the right formula to model the convection velocities and is unsure of how to apply the general convection-diffusion equation. They are also looking for guidance on slope field formulas and equations. They mention that they may need to change the shape of the pot to accurately model the process.
  • #1
cdrake3
3
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I have a difficult problem on my research exploration for math. I am modeling the convection currents of boiling water in a pot, which is heated by an electric stove. There is a constant supply of energy at 8000 watts (the average for a stove) that heats the pot from the bottom of the pot, which has a circular base.
My Assignment: I have to create a 2-D mathematical model for a convection current in a cylinder object with heat source on bottom late – then demonstrating a slope field for the velocity of water as it rises. I have to solve for various velocities throughout the position of the pot. For example, I must generate an equation that models this phenomenon and a 2-D Graph (slope field) from it – looking something like this (just an example – the below is not the correct graph for the convection situation that I’m modeling):

250px-Slope_Field.png
Where I’m Stuck: Currently, I’m not quite sure of how I should go approaching this problem; specifically what is the right governing math equation (formula) for this situation:

• 2-D convection current
• Cylindrical shape
• Circular plate heat source underneath (8,000 watts)

In addition, I need to find the right formula that will create a model for a slope field – such that I can product a graph from it (to model convection velocities).

I have some research done below – but I’m not finding the right-fit formula to address my problem. There seems to be several physics and mathematical expressions that come together for the solution I seek – but I don’t know how exactly or if I am following the right approach. Here goes:

General Convection-Diffusion Equation:
The general equation is:

d39e39a35d9a830eef04b24f2e5fd5aa.png


where
• c is the variable of interest (species concentration for mass transfer, temperature for heat transfer),
• D is the diffusivity (also called diffusion coefficient), such as mass diffusivity for particle motion or thermal diffusivity for heat transport,
• v is the average velocity that the quantity is moving. For example, in advection, c might be the concentration of salt in a river, and then would be the velocity of the water flow. As another example, c might be the concentration of small bubbles in a calm lake, and then would be the average velocity of bubbles rising towards the surface by buoyancy (see below).
• R describes "sources" or "sinks" of the quantity c. For example, for a chemical species, R>0 means that a chemical reaction is creating more of the species, and R<0 means that a chemical reaction is destroying the species. For heat transport, R>0 might occur if thermal energy is being generated by friction.
• ∇ represents gradient and represents divergence.

There is more information that I am using in the link below:
http://en.wikipedia.org/wiki/Convection–diffusion_equation#General

Where do I go from here?: from this point, I’m totally lost on if the above general equation is correct or not for my specific problem – and if it is, then how do I apply it?

Beyond that, I need to create a mathematical model for the slope field of convection current velocities – which is my ultimate aim for the overall assignment.

Can you help me to organize my approach from here?
How do I apply the general formula above? Considering that I have a 2-D cylinder problem and a 1-side heat source (bottom circle surface).
Do you have any guidance on slope field formulas/equations?

I thank you for your help in advance – I am hoping that you can help point me in the right direction.
 
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  • #2
I don't understand how you intend to create a 2D model of what is essentially a 3D process. If the plate is heated uniformly, convection can only occur by symmetry breaking (forming Bénard cells, as I recall). Seems to me you would have to change the 'pot' to be a thin vertical rectangular tank.
 

FAQ: Mathematical Model for Convection Current

What is a mathematical model for convection current?

A mathematical model for convection current is a set of equations that describe the behavior and movement of fluids or gases due to differences in temperature and density. It is used to predict the flow patterns and energy transfer in various systems, such as weather patterns, ocean currents, and heat transfer in engineering applications.

How is convection current related to temperature and density?

Convection current is directly related to temperature and density. When a fluid or gas is heated, it becomes less dense and rises, while cooler fluid or gas sinks due to its higher density. This creates a continuous flow, known as convection current, as the heated fluid or gas displaces the cooler fluid or gas.

What factors affect convection currents?

Several factors can affect convection currents, including the temperature difference between the heated and cooled areas, the properties of the fluid or gas, the shape and size of the container, and the presence of external forces such as wind or gravity. These factors can influence the speed, direction, and stability of the convection current.

How is a mathematical model for convection current developed?

A mathematical model for convection current is developed by analyzing the physical laws and principles that govern the behavior of fluids and gases, such as conservation of mass, momentum, and energy. These laws are then translated into mathematical equations that can be solved to predict the behavior of convection currents in various scenarios.

What are the limitations of a mathematical model for convection current?

Like any other mathematical model, a mathematical model for convection current has its limitations. It may not be able to accurately predict the behavior of complex systems or account for all the variables and factors that can affect convection currents. Additionally, it relies on simplifying assumptions, which may not always hold true in real-world situations. Therefore, it is essential to validate the results of a mathematical model with experimental data and make adjustments as necessary.

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