What is fluid shear stress?

Fluid shear stress is the force per unit area acting on a given fluid parallel to a surface cell. This occurs due to the component's force vector being parallel to the cross section.

Fluid shear stress contradicts the normal stress produced by the force vector. These force vectors are perpendicular to the acting cross-section of the material.

Fluid shear stress is also an important factor in determining the fate of stem cells. Applied technique, orientation pattern and size all affect cell fate and generate different patterns and proliferation.

Fluid shear produces mechanical stimulation at the cellular level. However, some fluids do not depend on fluid shear stress rate history. Time-independent and non-Newtonian fluids are often divided into shear-thickening, shear-thinning, and classically Newtonian. For accurate calculation of fluid shear stresses, the elements should be very small. In this case, the greatest source of stress is fluid viscosity.

In a straight vessel or flow within a vessel, the fluid does not move at the same speed at every point within the vessel. In this case the volume is slowest near the vessel wall and fastest in its focal region. The fluid velocity follows a laminar profile (or "parabola"). This flow is created by friction within the walls of the container and is related to the fluid viscosity.

A fluid moving along a solid boundary or surface necessarily generates shear stresses that rub against a given boundary. The no-slip condition enforces that the fluid velocity (relative to the boundary) at the boundary is always zero. However, at a certain height from the boundary, the flow velocity needs to be equal to that of the fluid. The region between the boundary and the height from the boundary, where the flow velocity is equal to the boundary of the fluid, is called the boundary layer.

For a Newtonian fluid in laminar flow, the shear stress is proportional to the rate of strain that may exist in the fluid, and this is where the viscosity is a constant ratio. Although, for non-Newtonian fluids, the viscosity is not constant; shear stress acts on the boundary due to this velocity loss.

Considering the medium used, shear stress can lead to significant changes in interlaminar fluid flow. Studying and understanding this phenomenon makes it possible to implement it in the design, monitoring, and control of systems that often include electronics for a wide range of applications in different fields such as automotive, aerospace, energy, and industrial processing.

In summary, fluid shear stress is the tangential force generated by friction created by a flowing fluid. The magnitude of fluid shear stress depends on the velocity of the fluid as it moves from and around the vessel; its rate should be monitored and accurately measured to prevent stress from causing corrosion.