deborah number

The Deborah number, a dimensionless number used in rheology, is named after her.

The non-dimensional Deborah number is designed to account for the degree of non-Newtonian behaviour in a flow.

Since Deborah number is a relative quantity, the numerator or the denominator can alter the number.

While Wi is similar to the Deborah number and is often confused with it in technical literature, they have different physical interpretations.

The Deborah number is a dimensionless number, often used in rheology to characterize the fluidity of materials under specific flow conditions.

At lower Deborah numbers, the material behaves in a more fluidlike manner, with an associated Newtonian viscous flow.

A very small Deborah number can be obtained for a fluid with extremely small relaxation time or a very large experimental time, for example.

At higher Deborah numbers, the material behavior changes to a non-Newtonian regime, increasingly dominated by elasticity, demonstrating solidlike behavior.

In contrast, the Deborah number should be used to describe flows with a non-constant stretch history, and physically represents the rate at which elastic energy is stored or released.

The Deborah number is defined as the ratio of the characteristic time of relaxation (which purely depends on the material and other conditions like the temperature) to the characteristic time of experiment or observation.

Small Deborah numbers represent Newtonian flow, while non-Newtonian (with both viscous and elastic effects present) behaviour occurs for intermediate range Deborah numbers, and high Deborah numbers indicate an elastic/rigid solid.

Formally, the Deborah number is defined as the ratio of the relaxation time characterizing the time it takes for a material to adjust to applied stresses or deformations, and the characteristic time scale of an experiment (or a computer simulation) probing the response of the material.