Describe the hypotheses behind the concept of boundary layer in immersed bodies. Under which conditions can we separate the inviscid region far from the wall from the viscous region close to the wall?

Select any two (2) areas of applications of chain-drive. (clo4) a)-permanent lubrication necessary b)-hydraulic forklift truck operation c)-rigging and heavy moving materials d)-relatively high maintenance costs e)-costlier than belt drives