Greenhouses play an important role in the field of agriculture, allowing the grower to have more control on the environmental factors that govern the behaviour of crops. The interactions of the environmental factors on the inside climate of a greenhouse are complex and involve a set of physical mechanisms that constitute challenges to modellers. To better assess the greenhouse climatic behaviour, a CFD modelling approach was developed and combined with field surveys considering a Venlo, closed greenhouse, under semi arid conditions. Measurements were undertaken at different heights along a vertical cross-section at the centre of the greenhouse. The components of the greenhouse were then integrated inside a CFD distributed climate model. The boundary conditions were inferred from the outside climatic conditions, taking account both of radiative and convective transfers through the walls. Simulations were conducted under pseudo-steady state conditions (i.e., updating the boundary conditions at each time step) all day long, and several scenarios (clear or cloudy day) were simulated to analyse to what extent the inside climate of the green¬house responds to the outside climate conditions.

Computational homogenization is demonstrated as a potential analysis tool that can be used directly to predict the property structure relationships of many existing classes of composites. Based on finite element simulations, using the Zebulon structures calculation code, the present study is devoted to computation and estimation the effective behavior of the nonlinear composite materials with randomly identical elastic perfectly plastic parallel cylindrical fibers distribution in linear elastic matrix phase. The parameters of effective behavior of the composite will be expressed. These parameters are the effective elastic tangent modulus, effective plastic tangent modulus and effective yield stress. The proposed method can be readily applied to compute the parameters of effective behavior composite, using a new proposed analytical expression based on the volume fraction and effective Young's modulus of each component. A good agreement between expression and simulation results is observed. Several examples are shown.