Two-dimensional CFD modeling
3.1 Computational domain and boundary conditions
The domain is modeled in ANSYS Fluent v15.0 in both two and three dimensions. The advantage of using a CFD
package rather than a ray tracing tool is that the CFD modeling provides an integrated environment for all
simulations to be completed in. This is particularly important when transferring information for the radiation
boundary condition from the two-dimensional model to the three-dimensional model.
The two-dimensional Computational Fluid Dynamics (CFD) model of the domain consists of both the mirror
field and a trapezoidal receiver with four collector pipes of diameter 50mm (See Figure 6). The 2-D model
functioned akin to a ray tracer, with discrete ordinates radiation modelling and fixed temperatures on all external
boundaries. The entire model consists of solid regions that do not conduct heat but participate in radiation. This
simulates the absorption and reflection in order to quantify the absorbed radiation flux on each collector pipe. The
absorbed radiation flux profile is then used in a user-defined function that patches it in as a heat source for the threedimensional
model, thereby reducing the required computational domain for the conjugate three-dimensional CFD
model, to be described next. The boundary conditions are listed in Table 1.