Inertia Dominated: Explaining Physically What It Means

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In summary, when ratios like Reynolds number or Weber number are very high, the physics is "inertia dominated." This means that the kinetic energy is so large that surface tension or other effects are negligible. However, some may argue that "inertia dominated" is not the most accurate term, as it implies something other than kinetic energy.
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K41
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So if we have ratios like Reynolds number or Weber number, i,e ratio of inertial to viscous forces and ratio of inertial to surface tension forces respectively, I've seen many texts say that when these non-dimensional numbers are very high, the physics is "inertia dominated".

I don't really understand what this means. Can anyone explain?

As an example, for Reynolds number, we say in high Re flows, inertia dominates at the large scales and in high velocity collisions, inertia dominates the surface tension, but what, physically, does that mean?

Thanks
 
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The kinetic energy is so large that surface tension or other effects are negligible.
 
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mfb said:
The kinetic energy is so large that surface tension or other effects are negligible.

I agree, I guess my concerns are that historically we've used "inertia dominated" to describe this when in my mind it is kinetic energy, and using the word "inertia" implies something else :s
 

1. What is inertia?

Inertia is the tendency of an object to resist changes in its motion. It is a property of matter that causes objects to stay at rest or in motion at a constant velocity unless acted upon by an external force.

2. How is inertia related to "inertia dominated"?

Inertia dominated refers to a system or situation where the effects of inertia are more significant than other forces or factors that may be present. This means that the behavior or motion of the system is primarily determined by the object's inertia.

3. How does inertia play a role in Newton's First Law of Motion?

Newton's First Law of Motion, also known as the Law of Inertia, states that an object will remain at rest or in motion with a constant velocity unless acted upon by an external force. This directly relates to the concept of inertia, as it is the property of matter that causes objects to follow this law.

4. Can inertia be measured?

Inertia is not a physical quantity that can be measured directly. However, its effects can be observed and measured through the study of an object's motion and the forces acting upon it.

5. How does inertia differ from momentum?

Inertia and momentum are related concepts, but they are not the same. Inertia is a property of matter that causes objects to resist changes in their motion, while momentum is a measure of an object's motion and is directly proportional to its mass and velocity. Inertia can be thought of as the property that gives an object its resistance to changes in its momentum.

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