Basset Force

Definition

Basset force refers to the additional force experienced by a particle in a fluid due to its acceleration history, specifically arising from the fluid's viscosity and inertia. This force plays a crucial role in the dynamics of particles suspended in a fluid, particularly when considering interphase momentum transfer, as it accounts for the effects of time-dependent forces acting on the particle as it moves through the fluid.

5 Must Know Facts For Your Next Test

1. The Basset force becomes significant in systems where particles are accelerating or decelerating, making it important in transient flow conditions.
2. Mathematically, the Basset force is often represented as a time integral of the velocity of the particle, reflecting its history of motion.
3. The effect of Basset force can alter particle settling rates and can influence dispersion in multiphase flow systems.
4. In high Reynolds number flows, Basset forces may be negligible compared to inertial and drag forces, but they are critical in low Reynolds number flows.
5. Understanding Basset force is essential for accurate modeling and prediction of particle behavior in various engineering applications, such as sediment transport and chemical reactors.

Review Questions

• How does the Basset force influence particle dynamics in multiphase flows?
  • The Basset force influences particle dynamics by accounting for the effects of a particle's acceleration history within the fluid. This additional force modifies the net motion of particles, especially during transient states where velocities change rapidly. As such, accurately incorporating Basset forces into models helps predict behaviors like settling rates and dispersion patterns more reliably in multiphase systems.
• Compare and contrast Basset force with drag force and discuss their roles in particle motion through fluids.
  • While drag force acts as a resistive force opposing a particle's motion through a fluid based on its current velocity, Basset force incorporates the effects of past accelerations on the particle. Drag force is instantaneous, whereas Basset force reflects a cumulative effect over time. Together, they help characterize the overall motion of particles, with drag providing immediate resistance and Basset offering insights into dynamic interactions that can occur during fluctuations in velocity.
• Evaluate the implications of neglecting Basset forces in modeling particle behavior within complex fluid systems.
  • Neglecting Basset forces can lead to inaccurate predictions of particle dynamics, particularly during transient events where velocities are not constant. This oversight may result in incorrect assessments of settling velocities and dispersion characteristics, which are crucial for processes like sediment transport and mixing in chemical reactors. A comprehensive understanding that includes Basset forces is vital for engineers and scientists aiming to design efficient systems or predict environmental behaviors involving multiphase flows.

Related terms

Drag Force:

The resistive force experienced by an object moving through a fluid, proportional to the object's velocity relative to the fluid.

Stokes' Law: A law that describes the force of viscosity on a spherical object moving through a viscous fluid, applicable at low Reynolds numbers.

Inertial Forces:

Forces that arise from the mass of an object and its acceleration, influencing how the object interacts with the surrounding fluid.