Ideal and Real Fluids

Ideal and real fluids fall under fluid mechanics. Fluid mechanics is a specific branch of science that essentially deals with understanding how fluids or liquids behave. Real fluids are divided into two categories; Newtonian and non-Newtonian fluids.

• Newtonian Fluids: When a real fluid’s gradient velocity or rate of shear strain is directly proportional to the shear stress. For example: Benzine and Water. 
• Non-Newtonian Fluids: When a real fluid’s gradient velocity or rate of shear strain is not directly proportional to the shear stress. For example: pastes and plasters.   

When it comes to fluids there are a number of considerations that have to be kept in mind like the properties of a certain fluid, flow rate, buoyancy, flow rate, viscosity, and so on. There are certain properties of a fluid, like density, specific volume, and viscosity. Viscosity is that property in a fluid that offers resistance against the flow of the fluid. 

Ideal and Real Fluids Differences

Fluid is something that has the capacity to flow or to be deformed under the continuous influence of a tangential or shear force. One will understand fluids in detail as one digs deep into ideal and real fluids. 

Therefore, one has to look at the points of difference between ideal and real fluids.

• The biggest point of difference between ideal and real fluids is the very situation of their presence. In simpler words, Ideal fluids are imaginary in nature which means they do not exist in nature. Whereas real fluids very much exist in nature. 
• Ideal fluids do not have any viscosity or can be said to have zero viscosity. Moreover, real fluids have viscosity. When a fluid is viscous, it essentially refers to the thickness of the fluid or the friction the fluid faces while fluid flows. Therefore, ideal fluids do not face the opposing force and have a non-viscous flow, while real fluids have a viscous flow. 
• Ideal fluids are incompressible. This means neither the density nor the volume of the fluid changes with pressure. Whereas, real fluids are very much compressible. Therefore, for real fluids, the density faces change due to pressure change. 
• Bulk modulus is infinite for ideal fluids. Bulk modulus inversely depends on the volume change. However, volume change for ideal fluids is zero. However, real fluids are subjected to volume change and therefore have finite bulk modulus. 
• As ideal fluids exist only in theory, it is not subjected to surface tension. However, for real fluids, the surface tension exists.

Formulas

Continuity equation

A0V0 = A1V1

Where,  

A0 =Region 1’s cross-sectional area

V0 = Region 1’s flow velocity

A1 = Region 2’s cross-sectional area

V1 = Region 2’s flow velocity

Bernoulli equation

This theory states that the speed of fluid flow is increased as a result of a simultaneous decrease in the potential energy of the fluid or a decrease in the static pressure on the fluid. 

The equation stands as follows:-

P+ ½ pv2 + pgh = P1 + ½ pv1 2 + pgh1

Where,

p = density of fluid

g = acceleration from the gravity

P = pressure on fluid at elevation 1

v= velocity of fluid at elevation 1

h= height of fluid at elevation 1

P1 = Pressure on fluid at elevation 2

v1= velocity of fluid at elevation 2

h1= height of fluid at elevation 2

Ideal and Real Fluids Example

An example of ideal fluid cannot be provided because it does not exist in the real world but only in theory. However, every fluid that we see around us like water, diesel, petro, honey, and so on are real fluids. Moreover, differences in viscosity can be found in real-life examples as honey is more viscous than water.

Conclusion

The topic of ideal and real fluids has been covered by providing an in-depth understanding of the differences between both fluids. Moreover, the ideal and real fluids formula has also been incorporated under the topic. Also, ideal and real fluid examples have been provided for a better understanding of the concept. The FAQs section will address the most probable queries that might arise. Also, the FAQs section provides additional information for a better understanding of the topic- ideal and real fluids.