MODELING AIR-FLOW INSIDE AND AROUND HOODS USED FOR PNEUMATIC CONTROL OF PEST INSECTS .1. DEVELOPMENT OF A FINITE-ELEMENT MODEL

A two-dimensional finite element model to simulate airflow inside and around hoods used for pneumatic control of pest insects is presented. The model is based on the 2-D Navier-Stokes equations. The Stream Upwi nd Petrov-Galerkin method (SUPG) is used to improve the modeling of th e highly convective zones. The contour element concept allows a more a ccurate simulation of the effects of the boundary layer in the immedia te proximity of the walls. Three different elements are used to discre tize the modelled surfaces and domains: a nine-node quadrilateral, a s ix-node triangle, and a three-node linear. These elements have three d egrees of freedom per summit node (u, v, p), the two components of the air velocity Vector and the static pressure respectively, and two deg rees of freedom per middle node (u, v). The numerical scheme of resolu tion relies on the use of the Newton-Raphson method. Preliminary tests show the potential of the model for simulating airflow under differen t conditions.