Consider a velocity field $$\overrightarrow V = K\left( {y\widehat i + x\widehat k} \right),$$ where $$K$$ is a constant. The vorticity, $${\Omega _z},$$ is

A flow field which has only convective acceleration is

A flow field which has only convective acceleration is

As the temperature increases, the thermal conductivity of a gas