We consider a model for the cyclic activity of young binary stars that accrete matter from the remnants of a protostellar cloud .
If the orbit of such a binary system is inclined at a small angle to the line of sight , then the streams of matter and the density waves excited in the circumbinary disk can screen the primary component of the binary from the observer .
To study these phenomena by the SPH ( smoothed particle hydrodynamics ) method , we have computed grids of hydrodynamic models for binary systems based on which we have constructed the light curves as a function of the orbital phase.The main emphasis is on investigating the properties of the brightness oscillations .
Therefore , the model parameters were varied within the following ranges : the component mass ratio q = M _ { 2 } :M _ { 1 } = 0.2 0.5 and the eccentricity e = 0 0.7 .
The parameter that defined the binary viscosity was also varied .
We adopted optical grain characteristics typical of circumstellar dust .
Our computations have shown that bimodal oscillations are excited in binaries with eccentric orbits , provided that the binary components do not differ too much in mass .
In this case , the ratios of the periods and amplitudes of the bimodal oscillations and their shape depend strongly on the inclination of the binary plane and its orientation relative to the observer .
Our analysis shows that the computed light curves can be used in interpreting the cyclic activity of UX Ori stars .

Key words : variable stars , binary stars , early evolutionary stages .