$5.$ The minimum $\_\_\_\_\_\_\_$ velocity is a crucial parameter for the operation of fluidized $\_\_\_\_\_\_\_$ reactors.

$6.$ Bubble column reactors utilize a $\_\_\_\_\_\_\_$ phase to enhance reactions or separations in a $\_\_\_\_\_\_\_$ medium.

$7.$ Trickle bed reactors are known for their high $\_\_\_\_\_\_\_$ transfer efficiency, particularly in $\_\_\_\_\_\_\_$ flow conditions.

$8.$ Flow regime identification in multiphase flow is vital for predicting $\_\_\_\_\_\_\_$ drop and optimizing $\_\_\_\_\_\_\_$ distribution.