Which type of flow corresponds to flow through an uninsulated pipe maintained at a constant temperature?

• A. Adiabatic
• B. Isobaric
• C. Isothermal
• D. Turbulent

Answer: (C)

Isothermal flow means the fluid’s temperature stays constant as it moves, while other properties like pressure or velocity can change. Here, the pipe is uninsulated but maintained at a fixed temperature by the surroundings, so heat can transfer between the fluid and the pipe walls. If this heat transfer is enough to keep the fluid at that same temperature throughout the pipe, the flow is isothermal. Adiabatic would mean no heat transfer, which isn’t the case with walls held at a constant temperature. Isobaric would require constant pressure, which isn’t specified, and turbulent describes flow roughness or mixing, not temperature. So the flow is isothermal.