безвихрова зона
irrotational motion of a fluid
irrotational velocity field
principle of persistence of irrotational flow
arid region
army readiness region
flight information region (FIR)
geostrategic region
strategic region
air defense region (ADR)
depot distribution region
ensure peace and stability in the region
hydrodynamic lubrication region
stagnation region
dead region
vorticity region
search and rescue region
simply coherent region
simply connected region
transition region
densely populated (densely-populated) area (region) / territory / country
confusion region
region of interest (ROI)