 # Difference Between Fluid And Newtonian Fluid

A fluid is a substance that deforms continuously when subjected to a shear stress. A simplified definition is that it is a substance that is able to flow smoothly and changes it’s shaped when a force is acted upon it. There are different types of fluids. Ideal Fluids and Newtonian as examples. An ideal fluid is a substance that has zero viscosity and is considered to be incompressible (density is constant).  In reality, there is no such thing as ideal fluids as there are always viscous effects, but are used to simplify calculations. A Newtonian fluid is a substance when there viscous stresses are linearly proportional to the shear rate.  Air behaves like an ideal fluid and is also a Newtonian Fluid. The flow field around a cylinder …show more content…
It is created by the interaction and contact of a solid body with a fluid. There are different types of drag such as induced drag, skin-friction drag and pressure (foam) drag. Induced drag in this experiment is not relevant as there isn’t a lift component acting of the object. Skin-friction is the drag caused by the interaction between the molecules of the fluid and the solid object. It is dependant of the viscous forces of the flow, viscosity of the fluid and the roughness of the surface of the solid object. Pressure drag, sometimes called foam drag, is generated due to the shape of the object. As the fluid flows around the body the local pressure and velocity changes. Pressure measures the momentum of the fluid molecules and if the pressure varies, a change in momentum produces a force.  In this experiment, key drag forces are the skin drag and pressure drag. The skin drag and pressure drag can be accumulated to get the total drag. The drag coefficient is the ratio of the drag force formed in comparison to the product of the dynamic pressure and area. It is a dimensionless quantity. The factors that affect the drag coefficient is the shape of the body, the roughness of the surface, the viscosity of the fluid and compressibility of the object. The viscosity of the fluid introduces the Reynold Number. In Engineering, a key concept to understand is the Reynolds Number. It is the ratio inertial forces (resistance to motion) compared to the viscous forces (fluid 's internal resistance to flow). It is dependent of the velocity, density characteristic length and dynamic viscosity. It is an important factor as it tell you what type of flow you can expect. It gives a quantitative value that tell us the flow is going to be smooth or unsteady, whether it be Laminar Flow or Turbulent Flow. At Low Reynolds number the viscous forces tend to be greater and via versa. The drag coefficient was calculated