Is Steady state an Eulerian or Lagrangian concept Explain yo

Is Steady state an Eulerian or Lagrangian concept? Explain your answer.

Solution

Steady state is an Eulerian concept.

Lagrangian and Eulerian are the two methods or approaches of study of fluid kinematics.

In langragian or particle approach individual fluid particles are selected and there behaviour is observed for studying the entire bulk of the fluid.( Here a fluid particle can be defined as any identifiable element of mass).Plotting the behaviour of the fluid particle with time gives pathline of the fluid particle. for eg. you are sitting in boat and drfiting down a river.

In Eulerian approach or point method , a point in a space occupied by the fluid in motion is selected and whatever changes take place in velocity, acceleration at that point are studied. e.g visualize you are siiting at the bank of river and watching the water pass the fixed location .

It is most commonly used approach and is applicable in all those cases where concept of continuum is valid. In this approach properties of flow field are defined as function of space cordinates and time.

Now from steady flow it is understood that the propeties of flow such as velocity, acceleration does not change with respect to time at any point in the flow field. So, definition clears that steady state is an Eulerian concept.