shear stress

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shear stress

the force acting in shear flow expressed per unit area; units in the CGS system: dynes/cm2.

shear stress

A frictional force tangential to the direction of a flowing fluid, the force of which is directly related to the fluid’s viscosity shear stress. In blood vessels, shear stress acts on endothelium and is the mechanical force responsible for the acute changes in luminal diameter. 

Stress parallel to a given surface (e.g., a fault plane) that results from forces applied parallel to the surface or from remote forces transmitted through surrounding rock.


(stres) [Fr. estresse, narrowness]
1. Any physical, physiological, or psychological force that disturbs equilibrium
2. The consequences of forces that disturb equilibrium.
3. Force applied per unit area. In the physical sciences, stresses include forces that deform or damage materials, such as impact, shear, torsion, compression, and tension. These physical stresses are particularly important in certain branches of health care, e.g., dentistry or orthopedic surgery, and in biotechnology industries, e.g., in the design and use of prostheses, grafts, and perfusion pumps.

Physiological stresses include agents that upset homeostasis, such as infection, injury, disease, internal organ pressures, or psychic strain.

In psychology, stresses include perceptions, emotions, anxieties, and interpersonal, social, or economic events that are considered threatening to one's physical health, personal safety, or well-being. Marital discord; conflicts with others; battle, torture, or abuse; bankruptcy; incarceration; health care crises; and self-doubt are all examples of conditions that increase psychic stresses. The response of an organism or material to stress is known as adaptation. See: adaptation; anxiety; fracture; homeostasis; Laplace, law of; relaxation response

critical incident stress

One's emotional reaction to a catastrophic event such as a mass casualty incident or the death of a patient or coworker. Often such events negatively affect the well-being of health care providers.

oxidative stress

The cellular damage caused by oxygen-derived free radical formation. The three most important are superoxide (O2-), hydrogen peroxide (H2O2), and hydroxyl ions; these are produced during normal metabolic processes as well as in reaction to cell injury. The extent of their damaging potential can be decreased by antioxidants.
See: antioxidant; free radical; superoxide; superoxide dismutase

prenatal stress

Anxiety, tension, depression, or other psychological discomfort experienced by a pregnant woman.

shear stress

References in periodicals archive ?
When assuming friction factor is constant at a given mass flow rate, wall shear stress can be expressed as a function of density and effective diameter.
[14] performed both numerical simulations and in vitro experiments on thoracic aorta to investigate the correlation of wall shear stress, pressure, and oscillatory wall shear stress index with aortic disorders, particularly aortic dissection.
The spatial and temporal variation of wall shear stress from the present study can be fed into other models to investigate the effect of wall shear stress on stresses and strains that individual endothelial cells may tolerate locally.
By applying a simple force balance (Bird et al., 2002) and assuming uniform wall shear stress in a given position along the pipe, the wall shear stress can also be determined by:
The changes in flow direction result in the directional changes in local wall shear stresses, which may injure the intima, particularly at the distal neck of the aneurysm.
To understand the actual physics of wall shear stress, the flow close to the boundary layer has to be accurately captured.
The major difference among these two models in predicting the wall shear stress is at the proximal neck region; the CFD model overestimates the wall shear stress by 30% compared to the FSI model at the deceleration phase.
Slip heating provides most of the heating at high exterior surface temperatures and wall shear stresses. Because both sources of temperature rise are of similar magnitude, neither should be neglected when correcting temperature data in flows where viscous dissipation matters.
The tundish construction described there in incorporates an impact pad to define the pouring area for the molten metal, curvature of tundish walls, wall inclinations, the depth of the inlet etc., The simulations were carried out with and without pouring chamber to understand the role of pouring chamber in the wall shear stress. It was found that pouring chamber has a dominant role in reducing the wall shear stress by modifying the fluid flow in the tundish.
where s is actual riblet spacing, v is the kinematic viscosity of the fluid, [s.sup.*] is a dimensionless expression of riblet spacing for which the range 10-20 has been determined to be optimal (11, 14), [[Tau].sub.w] is the wall shear stress due to the flow, and [Rho] is the fluid density.
The objective of this study was to investigate quantitatively the inspiratory and expiratory airflow characteristics (velocity, pressure, and wall shear stress) in tracheobronchial airways (G6-G9) of infant, child, and adult using CFD modeling.
The hemodynamic parameters of blood flow, such as blood pressure and arterial wall shear stress (WSS), provide important information about the pathophysiological mechanisms underlying vascular diseases [1].