How Drag Force Evolves in Global Common Envelope Simulations

Understand

We compute the forces, torque and rate of work on the companion-core binary due to drag in global simulations of common envelope (CE) evolution for three different companion masses.

• Our simulations help to delineate regimes when conventional analytic drag force approximations are applicable.
• During and just prior to the first periastron passage of the in-spiral phase, the drag force is reasonably approximated by conventional analytic theory and peaks at values proportional to the companion mass.
• Good agreement between global and local 3D "wind tunnel" simulations, including similar net drag force and flow pattern, is obtained for comparable regions of parameter space.