Abstract:

Heat and mass transfer in Engineering undergraduate courses are usually taught on the basis of analytical solutions to standard problems. The first step consists of analyzing the physical system in order to identify its actual characteristics and establish assumptions which allow setting up a manageable mathematical model of the phenomena of interest.

Even though a real system is always three-dimensional, a common assumption is to consider that the flow of heat or species occurs in only one or two dimensions. Another consideration includes whether the system is under steady- or unsteady-state. In our experience, the students have severe problems visualizing the physical meaning of these assumptions even when the professor draws them schematically in class.

In this paper, we report results of an ongoing project to generate video-clips of the evolution of the temperature or concentration fields for various physical situations involving the considerations described above. We have used the student version (freely available) of a finite element-based software to generate numerical solutions to several cases that will help the students visualize the system response; the powerful post-processing capabilities of the software allow presenting the results as: contour maps of temperature or concentration, vector maps of the heat or mass flow fields - the computed fields may be produced in the form of videos which may be readily distributed through Internet.

The basic cases considered are:
a) three-dimensional versus two-dimensional or one-dimensional heat or species flow;
b) steady- versus unsteady-state.

Furthermore, in the case of unsteady-state flow we have generated video-clips to illustrate the differences between systems without and with field gradients; in the latter case, we have included examples of finite and semi-infinite domains.

The video-clips are available through RUA (Red Universitaria de Aprendizaje – a university-wide learning repository) in order for professors of any Engineering course to used them freely.