Form drag predominates significantly over skin friction drag for which of the following object geometries?
Show answer Hide answer
Answer: C. Bluff body
Explanation
Bluff bodies create wide separated wake regions and strong pressure differentials behind them. Form drag caused by this pressure imbalance predominates significantly over skin friction drag. Streamlined bodies minimize wakes, whereas bluff bodies maximize form drag effects. Form drag arises from pressure differences between the front and rear of a moving body. Skin friction drag stems entirely from viscous shear stresses acting along solid surfaces. Bluff body geometries feature blunt leading or trailing edges causing flow separation.
Automotive designers streamline vehicle shapes to reduce aerodynamic form drag and save fuel. Cylindrical structures like smoke stacks experience high wind loads driven by form drag. Parachutes rely on maximizing form drag to decelerate rapidly through the atmosphere. Option A describes streamlined bodies where skin friction predominates over form drag. Option B is too general because two dimensional bodies can be either bluff or streamlined. Option D is wrong because bluff body geometry correctly identifies form drag dominance.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Under turbulent conditions, a rough pipe exhibits an identical friction factor to a smooth pipe when____________________?
Show answer Hide answer
Answer: B. When the roughness projections are much smaller than the thickness of the laminar film
Rough pipes exhibit smooth pipe friction factors when roughness projections are very small. Viscous laminar sublayer completely submerges and hides the interior roughness projections. Fluid flowing through the pipe inter...
Q2. In low Reynolds number flow regimes, drag force experienced by a sphere scales proportionally with_______________?
Show answer Hide answer
Answer: A. V
Stokes law governs low Reynolds number drag force, establishing linear velocity proportionality. Viscous forces dominate over inertial forces in creeping flow around small spheres. Doubling the fluid velocity results in...
Q3. Which type of fluid flow features flow velocity varying spatially from point to point at any given moment?
Show answer Hide answer
Answer: D. Non-uniform
Non-uniform flow features flow velocity varying spatially from point to point at any instant. Spatial velocity gradients distinguish non-uniform flow from uniform flow conditions. Changes in cross sectional area along a...
Q4. Fluid kinetic energy per unit weight, expressed as velocity head, is given by___________________?
Show answer Hide answer
Answer: B. v2/2gc
Velocity head represents kinetic energy per unit weight of flowing fluid systems. Dimensional analysis confirms that dividing kinetic energy by weight yields a length dimension. The exact gravitational conversion factor...
Q5. Interstage cooling units are incorporated into multistage compressors to____________________?
Show answer Hide answer
Answer: A. Save power in compressing a given volume to a given pressure
Interstage cooling removes heat generated during gas compression between successive machine stages. Cooling the gas decreases its specific volume, which directly reduces subsequent compression work. Multistage cooling cl...
Q6. In Newton’s law regime, the terminal velocity of a settling spherical solid particle varies inversely with ______________?
Show answer Hide answer
Answer: B. Inversely proportional to
In Newton's law settling regime, terminal velocity varies inversely with the square root of the fluid density or drag coefficient.