Bubbles in water, need a method/equations

In summary, the conversation discusses the need to determine the speed at which gas bubbles will travel from a variable depth in a liquid to the surface. The variables involved include liquid density, gas density, and temperature. The speaker is looking for a general guideline or equations to calculate this time for different gases in a homogenous liquid. They also mention the importance of calculating the maximum velocity of the gas. Some possible approaches suggested are using Stokes flow or taking into account the pressure and volume changes of the gas as it rises. The speaker also mentions the impact of temperature on the gas expansion.
  • #1
NCStarGazer
7
0
I have a need to know how fast gas bubbles will travel from a variable depth in a liquid to the surface. I realize there are a lot of variables here, liquid density, gas density, temp. etc... What I need is a general guideline for calculating the time with different gases through a homogenesis liquid. Any direction to a good article / study or equations is appreciated. Bottom line is probably stated as needing to know the rate of acceleration of a gas in a liquid to the surface, it will be important to be able to calculate the max velocity of the gas too. Example, if I had oxygen at 100 m under water and Helium 100 m under water at what rate will oxygen accelerate to the surface compared to Helium.

Thanks!
 
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  • #2
I'm not an expert in fluid dynamics, but it makes sense to me that your bubbles' speeds should only be a function of density. And if the density of fluids changes minimally with respect to temperature, you would need a function of density with the variable temperature.

I'm also not sure about this, but how quickly a bubble rises might be equivalent to how quickly water would fall in air but reversed. so if water falls in air at say 9.6 m/s^2, maybe air rises in water at that same acceleration
 
  • #3
You may be able to use Stokes flow, if the bubble is small enough to be nearly spherical. Then, the idea is simply F = ma, with the total force being a sum of buoyancy and drag forces.

http://en.wikipedia.org/wiki/Stokes'_law
 
  • #4
Given the bubbles are placed in the water at depth, i think you mentioned 100 M, they will start with a volume based on the pressure at this depth. I think one foot of depth is around .433 pounds for water, so 100 feet would be 43.3 psi and 300 feet (100 meter) 129.3 psi. The original pressure being 14.7 psi. the new pressure being 129.3 psi the volume at the top of water column will be 129.3/14.7 x (original volume of bubble). So its going to float faster as it expands up. That was a temperature constant observation, if the gas is allowed to expand rapidly the internal temperature of gas will drop retarding the volume expansion; less volume means less speed floating. Check out adiabatic gas laws and ideal gas laws.
 
  • #5


Dear researcher,

Thank you for your inquiry about calculating the speed of gas bubbles rising from different depths in a liquid. This is an interesting and complex topic that involves multiple variables. As you mentioned, the density of the liquid and gas, as well as temperature, can all affect the speed of the bubbles. Additionally, factors such as the size and shape of the bubbles, as well as any interactions with the surrounding liquid, can also impact their movement.

There are several methods and equations that can be used to estimate the speed of gas bubbles rising in a liquid. One commonly used equation is the Stokes Law, which takes into account the size and density of the bubble, as well as the viscosity of the liquid. This equation can provide a general guideline for calculating the time it takes for bubbles to reach the surface.

However, it is important to note that this equation may not accurately predict the exact speed of bubbles due to the many variables involved. Therefore, it is recommended to conduct experiments or consult existing studies to validate the results.

In terms of finding relevant articles or studies on this topic, a good starting point would be to search for keywords such as "gas bubbles rising in liquid," "Stokes Law," or "bubble dynamics." Additionally, consulting with experts in the field or reaching out to academic institutions or research organizations may also provide valuable insights and resources.

I hope this information helps guide your research and calculations. Please feel free to reach out for further clarification or assistance. Good luck with your project!

Sincerely,
 

1. What causes bubbles to form in water?

Bubbles in water are formed when gases, such as oxygen, nitrogen, or carbon dioxide, are released into the liquid. This can happen through various processes such as agitation, temperature changes, or chemical reactions.

2. How can I measure the size of bubbles in water?

To measure the size of bubbles in water, you can use a method called bubble counting. This involves counting the number of bubbles that rise to the surface of the water in a given amount of time. The size of the bubbles can then be estimated based on the average bubble count per unit of time.

3. Is there a mathematical equation for calculating the rate of bubble formation in water?

Yes, there is a mathematical equation that can be used to calculate the rate of bubble formation in water. It is known as the Higbie equation and takes into account factors such as bubble size, gas solubility, and liquid viscosity.

4. How can I control the formation of bubbles in water?

To control the formation of bubbles in water, you can try reducing the amount of gas present in the liquid by using a degassing agent or increasing the liquid's viscosity. You can also try minimizing agitation or using a lower temperature, as these factors can contribute to bubble formation.

5. Can bubbles in water affect the accuracy of my experiments?

Yes, bubbles in water can affect the accuracy of experiments that involve liquid measurements or reactions. This is because the presence of bubbles can alter the liquid's volume and composition, which can impact the results of the experiment. It is important to remove any bubbles before conducting precise experiments in water.

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