Drag Force
Drag Force - Related Videos
01:18
Drag Force and Terminal Speed
0 Views •
2023
An interesting force in everyday life is the force of drag on an object when it is moving in a fluid. Like friction, the drag force always opposes the motion of an object. Unlike simple friction, the drag force is proportional to some function of the velocity of the object in that fluid. This functionality is complicated and depends upon the shape of the object, its size, its velocity, and the fluid it is in. For most large objects, such as cyclists, cars, and baseballs, that are not moving too...
11:30
Buoyancy and Drag on Immersed Bodies
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2023
Source: Alexander S Rattner and Sanjay Adhikari; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA Objects, vehicles, and organisms immersed in fluid mediums experience forces from the surrounding fluid in the form of buoyancy- a vertical upward force due to fluid weight, drag- a resistive force opposite the direction of motion, and lift- a force perpendicular to the direction of motion. Prediction and characterization of these forces is...
01:23
Drag
0 Views •
2025
Drag is a resistive force opposing an object’s motion through a fluid, resulting from surface pressure and shear forces. It comprises two components: a perpendicular one from pressure and a tangential one from shear stress. Accurate drag calculations use pressure and wall shear stress distributions, often determined through Computational Fluid Dynamics (CFD) or wind tunnel testing. The drag coefficient, a dimensionless measure, depends on factors like shape, Reynolds number, Mach number, Froude...
08:57
Cross Cylindrical Flow: Measuring Pressure Distribution and Estimating Drag Coefficients
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2023
Source: David Guo, College of Engineering, Technology, and Aeronautics (CETA), Southern New Hampshire University (SNHU), Manchester, New Hampshire The pressure distributions and drag estimations for cross cylindrical flow have been investigated for centuries. By ideal inviscid potential flow theory, the pressure distribution around a cylinder is vertically symmetric. The pressure distribution upstream and downstream of the cylinder is also symmetric, which results in a zero-net drag force.
09:14
Paw-Dragging: a Novel, Sensitive Analysis of the Mouse Cylinder Test
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Cited by 53 •
2015
Classical forelimb asymmetry analysis of the cylinder test is routinely used to assess behavioural deficits in rats following brain injury or stroke; however, it fails to detect consistent deficits in mice. This study demonstrates that quantifying paw-dragging behaviour is a more sensitive analysis of brain injury in mice.
FAQs
Drag arises from momentum transfer at the object-fluid interface. Fluid viscosity contributes resistive effects as the fluid moves relative to the surface, while pressure differences develop around the body and add to the net opposing force. Considering both mechanisms helps engineers interpret why surface interaction and surrounding flow conditions matter when assessing motion through air or water.
At higher Reynolds numbers, engineers often use the relation F_D = 1/2 ρv²C_DA to estimate the force from fluid density, speed, drag coefficient, and projected area. This connection links a flow-condition measure to the variables used in engineering calculations, rather than treating drag as independent of the conditions under which the system operates.
The speed term is squared, so its contribution grows rapidly as motion becomes faster. If density, drag coefficient, and projected area remain unchanged, doubling speed multiplies the calculated drag by four. This makes velocity especially important in performance estimates because modest speed changes can produce substantial changes in resistive force and therefore influence energy use.
To estimate drag, engineers identify fluid density, object speed, drag coefficient, and projected area. They place those quantities in F_D = 1/2 ρv²C_DA, multiplying one-half the density by speed squared, coefficient, and area. The result provides a calculated force for the selected operating condition, supporting comparisons among designs or scenarios.
Drag force analysis is used in aircraft, vehicles, pipelines, wind turbines, and sports equipment. In each case, engineers can connect resistive force with practical design goals such as predicting speed, maintaining stability, or managing energy use. The same framework therefore supports very different systems, from moving vehicles to fluid-handling infrastructure and performance-oriented equipment.
In engineering, drag analysis supports efficiency by identifying how fluid resistance contributes to energy demands. Designers can use the resulting force estimates to guide efforts to reduce fuel consumption and improve performance. This is relevant wherever motion occurs through air or water, including transportation, wind turbines, and sports equipment, because resistive effects influence how effectively a system operates.