  In several B-type supergiants photometric and spectroscopic variabilities
together with episodes of enhanced mass-loss have been observed. Here we
present the preliminary results of linear stability analysis followed by
nonlinear numerical simulations in two B-type supergiants MWC 137 and MWC 314.
All the considered models of MWC 137 having mass in the range of 30 M$_{\odot}$
to 70 M$_{\odot}$ are unstable while for the case of MWC 314 models with mass
below 31 M$_{\odot}$ are unstable. The instabilities have been followed into
nonlinear regime for selected models of these two supergiants. During the
nonlinear numerical simulations, instabilities lead to finite amplitude
pulsation with a well defined saturation level in the considered models of MWC
137 with mass greater than 42 M$_{\odot}$. The model of MWC 314 with mass of 40
M$_{\odot}$ - the suggested mass for the primary star - does not show any
instabilities both in linear stability analysis and nonlinear numerical
simulations. Velocity amplitude reaches to 10$^7$ cm/s in the nonlinear regime
for the model of MWC 314 with mass of 30 M$_{\odot}$. Further extensive
numerical simulations and observations are required to understand the origin of
the observed variabilities in these stars.
