Natural convection streamline

Figure 9. Secondary flow natural convection streamlines for a zeroth order reaction and uniform viscosity at GrSc = 1, 10 and 10 . ...

In forced convection, the fluid is moved over the surface by a pump or blower neglecting natural convection are usually neglected. The study of forced convection is of great practical importance and vast amount of data have been amassed for streamline and turbulent flow in pipes, across and parallel to tubes, across plane surfaces, and in other important configurations such as jackets and coils. 

Natural convection and forced convection, depending respectively on the magnitude of buoyancy and the power of the pump or fan, may be laminar or turbulent. As we know from fluid mechanics, the streamlines of a laminar flow behave in an orderly manner, while the streamlines of a turbulent flow fluctuate irregularly about a mean flow. In this chapter, we shall deal with laminar convection. Turbulent convection will be left to Chapter 6. 

Though this value is fairly close to the assumed value of 64°C, a second iteration yields = 65°C. Thus, if the natural convection effects are ignored, the wall temperature at the end is found to be 55.5°C [see equation (i)] which is some 10°C lower than the value of 65°C. In a sense, this discrepancy also reflects the inherent inaccuracy of the predictive equations in this field. The value of Re i (using the apparent viscosity near the wall) is calculated and this confirms that the flow is streamline ... 

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