Numerical Simulation of the Airflow within a Canopy Using a 3D Canopy Structure

Canopy architecture of windbreaks is vital in agriculture,meteorological and ecological applications.In this study,computational fluid dynamics(CFD) and field experiments were used to investigate the flow characteristics and flow resistance through vegetation canopies with several different leaf area densities(L_(ad)).Compared with traditional modelling approaches,the present model introduced 3D architecture of the tree that contained a hard trunk,branches and artificial leaves to model the effect of leaves and the other parts of the canopy on airflow.Visual basic application(VBA) produced the 3D architecture of canopy.Simulations were made with the full closure model(FCM) and microcosmic model(MM).Canopies L_(ad),used in the simulations were7.76,18.12 and 25.89 m^(-1).The objectives of this paper are to analyze the contour of velocity(U) and turbulent kinetic energy(k)of two models in different leaf area densities,comparing the simulation results with experimental data/other works and investigate the real effects of the canopy on the airflow distribution.Results are encouraging,compared with the FCM,V and k of MM profiles qualitatively agree better with other works.Therefore,the model and method are recommended for future use in simulating turbulent flows in forest canopies.

Nasal airflow of patient with septal deviation and allergy rhinitis

A numerical simulation of a patient’s nasal airflow was developed via computational fluid dynamics.Accordingly,computerized tomography scans of a patient with septal deviation and allergic rhinitis were obtained.The three-dimensional(3D)nasal model was designed using InVesalius 3.0,which was then imported to(computer aided 3D interactive application)CATIA V5 for modification,and finally to analysis system(ANSYS)flow oriented logistics upgrade for enterprise networks(FLUENT)to obtain the numerical solution.The velocity contours of the cross-sectional area were analyzed on four main surfaces:the vestibule,nasal valve,middle turbinate,and nasopharynx.The pressure and velocity characteristics were assessed at both laminar and turbulent mass flow rates for both the standardized and the patient’s model nasal cavity.The developed model of the patient is approximately half the size of the standardized model;hence,its velocity was approximately two times more than that of the standardized model.

A cloud-based platform to predict wind pressure coefficients on buildings

Natural ventilation(NV)is a key passive strategy to design energy-efficient buildings and improve indoor air quality.Therefore,accurate modeling of the NV effects is a basic requirement to include this technique during the building design process.However,there is an important lack of wind pressure coefficients(CP)data,essential input parameters for NV models.Besides this,there are no simple but still reliable tools to predict CP data on buildings with arbitrary shapes and surrounding conditions,which means a significant limitation to NV modeling in real applications.For this reason,the present contribution proposes a novel cloud-based platform to predict wind pressure coefficients on buildings.The platform comprises a set of tools for performing fully unattended computational fluid dynamics(CFD)simulations of the atmospheric boundary layer and getting reliable CP data for actual scenarios.CFD-expert decisions throughout the entire workflow are implemented to automatize the generation of the computational domain,the meshing procedure the solution stage,and the post-processing of the results.To evaluate the performance of the platform,an exhaustive validation against wind tunnel experimental data is carried out for a wide range of case studies.These include buildings with openings,balconies,irregular floor-plans,and surrounding urban environments.The C_(P) results are in close agreement with experimental data,reducing 60%-77% the prediction error on the openings regarding the EnergyPlus software.The platform introduced shows being a reliable and practical C_(P) data source for NV modeling in real building design scenarios.