'IdealFluid' Describe Behavior of Matter in Phase State of liquid/gas+

In summary, there are inconsistencies in the terminology used in Continuum Mechanics, particularly with the terms "Ideal Fluid" and "Ideal Solid". While "Ideal Fluid" describes the behavior of matter in liquid or gas phase states, "Ideal Solid" describes the behavior in solid or liquid phase states. However, historically, "Solid" has been used to describe both the phase state and matter behavior. The term "Solid Mechanics/Dynamics" should be updated to avoid confusion. Additionally, there may be a need for a more general term for solids, similar to the term "Fluid" for liquids and gases. However, since terminology is established over time, it may not be possible to change it. Furthermore, other terms such as "un-hollow
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One thing about terminology that I think c/should be changed for Continuum Mechanics:

1) 'Ideal Fluid' Describe Behavior of Matter in Phase States of liquid/gas and sometimes Bulk-Solid:

-continually deform under applied shear stress or external force
-usually zero shear modulus
-behavior can further be specified by Constitutive Material model for that fluid, e.g. viscoelasticity2) 'Ideal Solid' Describe Behavior of Matter in Phase States of Solid and sometimes Liquid:

-usually NON-zero shear modulus
-behavior can further be specified by Constitutive Material model for that solid, e.g. elasticity, plasticity, viscoelasticity
-solid-continua and structure elements

3) Historically, it's understood Solid describes both phase state & matter behavior, whereas Fluid describes matter behavior for variety phase states

-So instead of Solid Mechanics/Dynamics, I think that this term should be updated
-is there more general term instead of solid, as in the same spirit as fluid term? Any suggestions?
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PS, by the way term solid is also used when describing e.g. cylinder that is not hollow, but again solid refers to phase state of matter. Is there more rigorous term than 'solid or un-hollow' to describe object that is not hollow?
 
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  • #2
Lou Tkach said:
One thing about terminology that I think c/should be changed for Continuum Mechanics:
Terminology develops over time and that haphazard development sometimes leads to inconsistencies in usage or the same word being used in different ways in different contexts. You've found one of these.

The terminology may not be optimal, but it it is what it is and there's no way of changing it once it's established. Because there's not much to do here except recognize that the terminology is what it is, this thread is closed.
 
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1. What is an ideal fluid?

An ideal fluid is a theoretical concept in fluid mechanics that describes a fluid with no viscosity or internal friction. It is also assumed to have a constant density and be incompressible.

2. What is the behavior of matter in the liquid/gas phase state?

In the liquid/gas phase state, matter behaves as a fluid, meaning it can flow and take the shape of its container. The molecules are also constantly moving and colliding with each other, but they have enough energy to overcome the attractive forces between them, allowing the substance to exist in a gaseous state.

3. How does an ideal fluid differ from a real fluid?

An ideal fluid is a simplified model that does not exist in reality, while a real fluid takes into account factors such as viscosity, compressibility, and density variations. Real fluids also experience energy losses due to friction, whereas an ideal fluid does not.

4. What are some applications of ideal fluids?

Ideal fluids are often used in theoretical calculations and models in fluid mechanics, such as in Bernoulli's equation and the ideal gas law. They can also be used to study the behavior of real fluids in certain situations, such as in low-viscosity liquids or high-temperature gases.

5. Can any real fluids be considered ideal?

No, no real fluids can be considered ideal as they all have some degree of viscosity and compressibility. However, in certain situations, such as in low-speed and low-viscosity flows, the effects of viscosity may be negligible, making the fluid behave similarly to an ideal fluid.

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