In this study, we examine the effect of boundary conditions, both infl
ow and outflow, on the predicted flow fluctuations in a supersonic Set
entering into a subsonic outer flow. Various boundary conditions are
used to compute the flowfield of a laminar axisymmetric jet excited at
the inflow by a disturbance given by the corresponding eigenfunction
of the linearized stability equations. Our goal is to determine the su
itability of these conditions for computations of time-dependent flows
. We solve the full time-dependent Navier-Stokes equations by a high-o
rder numerical scheme. For very small excitations, the computed growth
of the modes closely corresponds to that predicted by the linear theo
ry. We then vary the excitation level and examine the effect of the bo
undary conditions in the nonlinear flow regime.