Drag Coefficient
Drag Coefficient - Related Videos
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.
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
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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...
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.
01:18
Drag Force and Terminal Speed
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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...
FAQs
The drag coefficient can change when Reynolds number or flow regime changes, even if the body geometry remains the same. Consequently, a value measured under one operating condition may not represent performance at another speed or fluid condition. Engineers account for these dependencies when predicting aerodynamic or hydrodynamic behavior, particularly when applying experimental results or correlations to a design.
Body shape and surface roughness influence how strongly a fluid resists motion around a body, so they can change the resulting coefficient. The reference area also matters because it provides the area used to relate drag force to density, speed, and coefficient. Consistent geometry, surface condition, and reference-area conventions are therefore essential when comparing engineering designs or datasets.
A drag coefficient provides a dimensionless way to relate resistance to fluid density, flow speed, and a chosen reference area, whereas drag force is the resulting physical load. The force can therefore change when speed, fluid density, or area changes, even if the coefficient remains the same. This distinction helps engineers separate body-related behavior from operating-condition effects.
Engineers can determine a drag coefficient through experiments, simulations, or standardized correlations. The selected approach should represent the body shape, surface condition, fluid environment, speed, and relevant flow regime under consideration. Comparing results obtained under matching conditions improves confidence in the value, while mismatched conditions can produce misleading estimates of aerodynamic or hydrodynamic performance.
Once an appropriate value is available, engineers can estimate drag forces from fluid density, flow speed, and reference area. Those force estimates support calculations of power requirements, fuel consumption, and stability. In this way, the coefficient connects fluid-flow behavior with practical design decisions, allowing performance consequences to be considered before or alongside physical testing.
Drag coefficient analysis applies across systems that move through air or water, including aircraft, automobiles, pipelines, wind turbines, and underwater vehicles. Its use varies with the design objective: engineers may examine aerodynamic or hydrodynamic resistance, energy demand, fuel consumption, or stability. The same framework supports comparison and prediction across these diverse fluid-environment applications.