MTH642 Midterm Subjective by Abbas

Mth642 Mid Term Subjective.

Short Question.

Q1. Define the term Fluid?

Answer: A substance in the liquid or gas phase is referred to as a fluid.

Q2. Define the term Stress?

Answer: Stress is defined as force per unit area and is determined by dividing the force by the area upon which it acts.

Q3. Define the term Normal Stress?

Answer: The normal component of the acting on a surface per unit area is called the normal stress.

Q4. Define the term Shear Stress?

Answer: The tangential component of force acting on a surface per unit area is called the shear stress.

Q5. What is a Pressure?

Answer: In a fluid at rest, the normal stress is called Pressure.

Q6. What is No-Slip Condition?

Answer: the flow of a fluid in a stationary pipe or over a solid surface that is nonporous solid “sticks” to the surface due to viscous effects and there is no slip. This is known as the no slip condition.

Q7. Define the term Boundary Layer?

Answer: The flow region adjacent to the wall in which the viscous effects are significant is called the boundary layer.

Q8. What is Flow Separation?

Answer: When a fluid is forced to flow over a curved surface, such as the back side of the cylinder at sufficiently high velocity the boundary layer can no longer remain attached to the surface and at same point it separates from the surfacea process called flow separation.

Q9. Define the term Viscous Flows?

Answer: Flows in which the frictional effects are significant are called viscous flows.

Q10. Define the term Incompressible Flow?

Answer: Incompressibility is an approximation, in which the flow is said to be incompressible if the density remains nearly constant throughout.

Q11. What is Super Sonic and Sub Sonic?

Answer: Super Sonic: A flow is called Super Sonic when Mash Number (Ma)>1. Sub Sonic: A flow is called Sub Sonic when Mash Number (Ma)<1.

Q12. Define the term Laminar Flow?

Answer: The highly ordered fluid motion characterized by smooth layers of fluid is called laminar flow.

Q13. Define the term Steady and Un Steady Flow?

Steady Flow:

The term steady implies no change of properties, velocity, temperature, etc., at a point with time.

Un Steady Flow:

The term Un Steady implies change of properties, velocity, temperature, etc., at a point with time.

Q14. Write about Transient Term in N-S Equation?

Answer: Transient terms in N-S equations are zero. ⇒ ∂u/∂t=∂p/∂t=0.

Q15. Define the term Surrounding and Boundary?

Answer: Surrounding: The mass or region outside the system is called the surroundings Boundary: The real or imaginary surface that separates the system from its surroundings is called the boundary.

Q16. Define the term Isolated System?

Answer: even energy is not allowed to cross the boundary, that system is called an isolated system.

Q17. Write Full Form of USCS?

Answer: The full form of USCS is “United States Customary System”.

Q18. Define the term Significant Digits?

Answer: Significant digits are digits that are relevant and meaningful. When performing calculations or manipulations of several parameters.

Q19. Define the term Density and write it’s formula and unit?

Answer: Density is defined as mass per unit volume. Formula: Density=ρ=m/v. Unit: ρ=kg/m3.

Q20. Define the term Specific Gravity and write its formula?

Answer: Specific Gravity is defined as the ratio of the density of a substance to the density of some standard substance at a specified temperature

Q21. Define the term Cavitation?

Answer: A phenomenon, which is a common cause for drop in performance and even the erosion of impeller blades, is called cavitation.

Q22. Define the term Viscosity?

Answer: It appears that there is a property that represents the internal resistance of a fluid to motion or the “fluidity” and that property is the viscosity.

Q23. Define the term Drag Force?

Answer: The force a flowing fluid exerts on a body in the flow direction is called the drag force.

Q24. Write about Fluid Velocity in Steady Laminar Flow?

Answer: In steady laminar flow, the fluid velocity between the plates varies linearly between 0 and V, and thus the velocity profile and the velocity gradient are: ⇒ u(y)=(y/l)V and du/dy=V/l. Where y is the vertical distance from lower plate.

Q25. Write Angular Displacement or Deformation Formula?

Answer: The Formula is: ⇒ dβ≈tandβ=da/t=vdt/l=(du/dy)dt

Q26. Define the term Newtonian Fluids?

Answer: Fluids for which the rate of deformation is linearly proportional to the shear stress are called Newtonian fluids.

Q27. Define the term Surface Tension and write its unit?

Answer: The magnitude of this force per unit length is called surface tension or coefficient of surface tension 𝜎s and is usually expressed in the unit N/m (or lbf/ft in English units).

Q28. What is Meniscus?

Answer: The curved free surface of a liquid in a capillary tube is called the meniscus.

Q29. Write Pressure Difference Formula?

Answer: The pressure difference between any two points 1 and 2 is: ⇒ △P=P2−P1=−∫12 ρgdz. If. P1=P2. ⇒F1/A1=F2/A2. ⇒ F1/F2=A1/A2.

Q30. What is Advective Acceleration?

Answer: The term (V→.▽→)V→ is called the advective acceleration and It accounts for the effect of the fluid particle moving to a new location in the flow.

Q31. Define the term Material Derivative and write its formula?

Answer: The total derivative operator d/dt is called the material derivative.

Formula:

⇒ D/Dt=d/dt=∂/∂t+(V→.▽→).

Q32. Write Full Form of CFD?

Answer: The full form of CFD is “computational fluid dynamics”.

Q33. What is a Streamline and write it’s formula?

Answer: A streamline is a curve that is everywhere tangent to the instantaneous local velocity vector.

Formula: In XY-Plane:

⇒ (dy/dx)along a Streamline =v/u.

Q34. What is a Path lines?

Answer: A path line is the actual path traveled by an individual fluid particle over some time period.

Formula:

⇒ x=x(start)+∫t(start)1 Vdt.

Q35. Define the term Linear Strain Rate and Shear Strain Rate?

Answer: Linear Strain Rate: Linear strain rate is defined as the rate of increase in length per unit length.