An Etymological Dictionary of Astronomy and Astrophysics
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Fluid mechanics: Having no → viscosity. Same as → inviscid.

From → non- + → viscous.

Having the property of → viscosity. See also: → viscous dissipation, → viscous decretion disk, → viscous fluid, → viscous force, → nonviscous.

M.E., from M.Fr. viscous, from L. viscosus "sticky," from viscum "anything sticky; mistletoe."

From vošk "a kind of sticky gum" + -sân suffix of similarity, from sân "way, manner."

A model for explaining several observational features of → circumstellar disks around → Be stars. According to this model, the central star provides → angular momentum to the disk at the innermost radius, and then it is redistributed over the whole disk via → viscosity. Thus, in isolated Be stars, the equatorial disk can spread out to a large distance as long as the star can give angular momentum to the disk. The VDD model, first introduced by Lee et al. (1991, MNRAS, 250, 432) and further developed by several other researchers, is now widely accepted as the best physical model for describing the circumstellar disks of Be stars. Among the growing evidence supporting the VDD model is the confirmation that the disks rotate in a Keplerian way (→ Keplerian orbit), allowing for the identification of viscosity as the mechanism that makes the disk grow (see, e.g., Klement et al., 2015, A&A 584, A85).

→ viscous; → decretion; → disk.

A degradation of → mechanical energy that is irreversibly converted to → thermal energy due to → viscous forces in the → fluid. Viscous dissipation occurs in → turbulent flows.

→ viscous; → dissipation.

A fluid whose viscosity is sufficiently large to make the viscous forces a significant part of the total force field in the fluid.

→ viscous; → fluid.

The force per unit volume or per unit mass arising from the action of tangential stresses in a moving → viscous fluid.

→ viscous; → force.