A new instability mode in fluidized beds

It is shown that the state of "isothermal" homogeneous fluidization can be linearly unstable to small-amplitude "non-isothermal" disturbances transver se to the direction of gravity. Conditions for instability of this new mode are examined and the marginal stability conditions are derived. The underl ying physical mechanism of the instability is discussed and contrasted with the widely known particle-phase-inertia driven longitudinal modes of plana r instability voidage waves.