Double Skin Façade CFD Simulation

Double-Skin Facade CFD Analysis: Thermal Buoyancy Effects in Building Ventilation

Computational Modeling of Natural Ventilation in Double-Skin Building Facades

This CFD project investigates airflow dynamics within a double-skin facade system using ANSYS Fluent simulation. The analysis focuses on thermal buoyancy effects that drive natural ventilation, an increasingly important sustainable building technology.

Geometric Configuration and Physical Model

The three-dimensional model represents a rectangular double-skin facade (0.6m × 3.2m × 5m) comprising two primary components: a glass section that captures solar radiation and an air channel that facilitates thermal convection. The system includes a 0.2m rectangular inlet valve positioned at the lower glass wall boundary and a corresponding outlet valve at the upper boundary, creating a natural ventilation pathway.

Numerical Approach and Boundary Conditions

The computational domain was discretized using ANSYS Meshing, generating 490,725 elements for accurate flow resolution. The simulation incorporates several key physical parameters:

- Glass section modeled with constant volumetric heat generation (6940 W/m³) to simulate solar radiation
- Building walls defined as brick material with convective boundary conditions (heat transfer coefficient: 23 W/m²K)
- Interior building temperature maintained at 300K
- Inlet air temperature specified at 304.55K with atmospheric pressure conditions
- Density variations captured using the ideal gas law to accurately model buoyancy effects
- Gravitational acceleration (9.81 m/s²) included to drive natural convection

Thermal Performance Visualization

The analysis produces comprehensive two-dimensional and three-dimensional visualizations of temperature distributions, pressure fields, and velocity patterns throughout the facade system. Vector plots clearly demonstrate the upward air movement driven by thermal buoyancy forces, confirming the effectiveness of the passive ventilation mechanism.

Sustainable Building Design Implications

Results validate the fundamental operating principle of double-skin facades, where solar-heated air creates a natural convection current that can be harnessed for building climate control. This passive ventilation approach offers significant potential for reducing mechanical cooling requirements and improving building energy efficiency.

The simulation provides valuable insights for architects and engineers seeking to optimize double-skin facade designs for maximum thermal performance across different environmental conditions.