2.3 Computational fluid dynamics Computational fluid dynamics or commonly abbreviated as CFD is the branch of fluid dynamics which is applied to simulate fluid flow, heat transfer, and associated phenomena such as chemical reactions by the numerical solution of the governing equations to analyze complex flows system such as complex turbulent flow (Versteeg and Malalasekera, 1995). Therefore, CFD has often been provided as the tool for testing of conditions which are not possible or difficult to measure experimentally in addition to a regular part of the process design. Moreover, virtual testing with CFD can be reduced development costs, saved development time, and eliminated rework and delays (Sayma, 2009). Due to these advantages, CFD rapidly
…show more content…
There are two types of flow models, laminar model and turbulence models. The type of model depends on the flow conditions; in other words, flow regimes of the system must be considered before selecting one of the models from abovementioned. Nondimensionless number, that is Reynolds number (Re), is used to indicated flow regimes. Laminar flow occurs at low Reynolds number, whereas turbulent flow occurs at high Reynolds number. The Reynolds number, which is the ratio of inertial forces to viscous forces, can be expressed as follows:
Re= ρvd/μ Where Re is Reynolds number, ρ is fluid density (kg⁄m^3 ), v is mean fluid velocity (m⁄s), μ is dynamics viscosity (kg⁄(m∙s)), and d is characteristic length (depending on the application, it can be geometry length or diameter) (m). Hydraulic diameter of channel is taken as d in the case of internal flows. While in the case of external flows, d is equal to the length of an obstacle in the direction of flow. In our system, high Reynolds number turbulent flow was found, then turbulence model was used in our study. In addition, energy equation, source term for porous media, and equation of motion for particle were also used in order to complement the simulation of an IQF which its airflow contains chicken scraps. The detailed of these equations are described
There are two types of flow models, laminar model and turbulence models. The type of model depends on the flow conditions; in other words, flow regimes of the system must be considered before selecting one of the models from abovementioned. Nondimensionless number, that is Reynolds number (Re), is used to indicated flow regimes. Laminar flow occurs at low Reynolds number, whereas turbulent flow occurs at high Reynolds number. The Reynolds number, which is the ratio of inertial forces to viscous forces, can be expressed as follows:
Re= ρvd/μ Where Re is Reynolds number, ρ is fluid density (kg⁄m^3 ), v is mean fluid velocity (m⁄s), μ is dynamics viscosity (kg⁄(m∙s)), and d is characteristic length (depending on the application, it can be geometry length or diameter) (m). Hydraulic diameter of channel is taken as d in the case of internal flows. While in the case of external flows, d is equal to the length of an obstacle in the direction of flow. In our system, high Reynolds number turbulent flow was found, then turbulence model was used in our study. In addition, energy equation, source term for porous media, and equation of motion for particle were also used in order to complement the simulation of an IQF which its airflow contains chicken scraps. The detailed of these equations are described