Definition

1. Noun:
   • A measure of a fluid's internal resistance to flow when a shear force is applied: Dynamic viscosity quantifies how much a fluid resists deformation or movement when subjected to a tangential force. It describes the "thickness" or "stickiness" of a fluid in motion.
   • A key property in fluid mechanics: It is a fundamental parameter used to characterize how fluids behave under stress, influencing flow rates, energy losses, and heat transfer.

Usage Examples

• Noun:
  • Engine oil has a higher dynamic viscosity than water, which is why it flows more slowly.
  • The engineer calculated the dynamic viscosity of the polymer solution to design the pump correctly.
  • A change in temperature significantly affects the dynamic viscosity of most fluids.

Advanced Usage

• "Shear-dependent dynamic viscosity": Refers to fluids whose viscosity changes with the applied shear rate (e.g., non-Newtonian fluids like ketchup or blood).

  • The non-Newtonian fluid exhibited shear-thinning behavior, meaning its dynamic viscosity decreased as the shear rate increased.

• "Kinematic viscosity vs. dynamic viscosity": Kinematic viscosity is the ratio of dynamic viscosity to fluid density.

  • While dynamic viscosity measures internal resistance, kinematic viscosity accounts for both resistance and inertial effects by incorporating density.

Variants and Related Words

• Viscosity (n): A more general term for a fluid's resistance to flow. Dynamic viscosity is a specific type of viscosity.

  • The viscosity of honey is what makes it drip slowly.

• Absolute viscosity (n): Another term for dynamic viscosity.

  • The data sheet lists the absolute viscosity of the lubricant at various temperatures.

• Newtonian fluid (n): A fluid whose dynamic viscosity remains constant regardless of the applied shear rate.

  • Water and air are common examples of Newtonian fluids.

Synonyms

• Absolute viscosity: The direct synonym for dynamic viscosity.
• Shear viscosity: Emphasizes that the property is defined in response to shear stress.

Related Phrases

• Viscosity coefficient: Often used interchangeably with dynamic viscosity in equations.

  • The Navier-Stokes equations include the viscosity coefficient to model fluid motion.

• Dynamic viscosity measurement: The process of determining this property.

  • The lab is equipped for precise dynamic viscosity measurement using a rotational viscometer.

Noun

1. a measure of the resistance to flow of a fluid under an applied force