Utilize the idea of minimum surface area to volume ratio (for cuboid, cylinder, 6 marks cone, sphere etc.) design the best shape for a riser using the chvorinov's rule. then design the best shape from practical point of view. hint: riser have molten material for longest time.

Afull journal bearing has a journal diameter of 27 mm, with a unilateral tolerance of -0.028 mm. the bushing bore has a diameter of 27.028 mm and a unilateral tolerance of 0.04 mm. the l/d ratio is 0.5. the load is 1.3 kn and the journal runs at 1200 rev/min. if the average viscosity is 50 mpa-s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.