Hydraulics and Fluid Mechanics Questions

• Submerged Body Stability – Relative Positions of Centers A fully submerged body is in stable equilibrium if its center of gravity lies below its center of buoyancy, so a small angular displacement produces a righting moment.
• Fluid Behavior – Viscosity Independent of Shear Rate A fluid whose viscosity remains constant regardless of the rate of shear is termed a Newtonian fluid. Water, air, and light oils are common examples.
• Footstep Bearing – Power Absorbed by Viscous Resistance For a flat circular footstep bearing of radius R rotating at angular speed omega with oil film thickness h and viscosity mu, the power absorbed in viscous shear can be computed from the viscous torque acting on the plate.
• Hydrostatics – Total Force on an Inclined Plane Surface For a plane area A immersed in a liquid and inclined at angle theta to the free surface, the total hydrostatic pressure equals w * A * x_cg, where w is specific weight and x_cg is the vertical depth of the area's centroid below the free surface.
• Flow Regime – Definition of Non-Uniform Flow A flow in a pipe or channel is called non-uniform when the mean velocity changes from section to section along the direction of flow, even if discharge is steady in time.
• Venturi Flume – What It Measures in Open Channels A Venturi flume is an open-channel primary device that accelerates flow through a throat to relate water level to discharge using calibrated curves.
• Pressure Scales – What a Gauge Indicates The pressure read directly on a mechanical or electronic pressure gauge equals gauge pressure, which is pressure above or below the local atmospheric reference.
• Transition in Internal Flow – Definition of Critical Velocity The critical velocity is the characteristic mean velocity at which internal flow in a duct shifts from laminar to turbulent, commonly identified using a threshold Reynolds number.
• Compressible Flow Regimes – Hypersonic Definition by Mach Number A flow is termed hypersonic when the Mach number is significantly greater than supersonic values; in engineering practice hypersonic usually means Mach number greater than 5.
• Fluid Mechanics — Definition of Reynolds Number In civil and mechanical engineering fluid dynamics, the Reynolds number (Re) is defined as the ratio of the inertia force to which other characteristic force acting within the fluid? Choose the most appropriate classification that appears in the standard definition.
• Orifice and Vena Contracta — Coefficient of Contraction A jet of water issues from a 40 mm diameter orifice. At the vena contracta, the jet diameter is measured as 32 mm. Compute the coefficient of contraction (Cc) using area ratio.
• Hydrostatics — Pressure at Depth in a Liquid For a static liquid, the pressure intensity p (in kN/m^2 or kPa) at a depth h below the free surface is given by which expression in terms of specific weight w?
• Rectangular Notch (Sharp-Crest) — Head–Discharge Relation In a standard sharp-crested rectangular notch, how does discharge Q vary with the head H measured above the crest, ignoring submergence and applying an appropriate coefficient?
• Capillarity in a Narrow Tube — Rise/Fall Height Formula A clean glass tube of small inside diameter d is dipped vertically into a liquid. What is the expression for the capillary rise (or fall) height h in terms of specific weight w, angle of contact alpha, and surface tension sigma?
• Pressure Measurement — Can Vacuum Pressure Be Read with a Piezometer? Consider a simple piezometer tube (open to atmosphere at the top). Can it be used to measure vacuum (below-atmospheric) pressure at a tapping point in a pipeline?
• Weir Calibration — Bazin’s Observation on Coefficient of Discharge According to Bazin's experiments on sharp-crested weirs, does the coefficient of discharge (Cd) vary with the height of water (head) over the sill/crest?
• Kinematic Viscosity from Poise and Specific Gravity An oil has specific gravity S = 0.95 and dynamic viscosity mu = 0.011 poise. What is its kinematic viscosity nu in stokes (1 stoke = 1 cm^2/s)?
• Rheological Classification — Water is Best Described As: In terms of how shear stress relates to rate of shear strain (rheology), water is best classified as which type of fluid?
• Droplet Shape — Why Falling Water Drops Tend to Spheres Falling drops of water tend to assume a spherical shape predominantly due to which physical property of water?
• Statement on coefficient of discharge (Cd) and actual discharge through an orifice: If the value of Cd increases, the discharge through the orifice decreases. State whether this statement is true or false.