1,721,068 research outputs found
Simulation of Time-dependent Flow in Cavities with the Additive Correction Multigrid Method, Part I: Mathematical Formulation
No full textNUMERICAL HEAT TRANSFER - PART B: FUNDAMENTAL
Simulation of Time-dependent Flow in Cavities with the Additive Correction Multigrid Method, Part II: Applications
No full textNUMERICAL HEAT TRANSFER - PART B: FUNDAMENTAL
Comparison of Turbulence Models for Side-Heated Cavities
No full textThe present work reports the comparison of different k-eps turbulence models for two-dimensional, differentially heated, rectangular enclosures. The comparison is related to the proiposed Benchmark excercise for the 22o Eurotherm/Ercoftac Workshop, i.e. a side-heated square cavity with a fluid with a Prandtl number of 0.71 and a Rayleigh number of 5x10^10, but further results are reported for enclosures with different aspect ratios and different Pr and Ra numbers, when experimental data are available. From the comparison, it is concluded that the standard k-eps turbulence model leads to severe errors in the prediction of mean quantities very close to the wall, like the heat transfer rate, while better agreement with the experiments is obtained with selected low-Reynolds-Number k-eps models
Node generation in complex 3D domains for heat conduction problems solved by RBF-FD meshless method
Full text linkA novel algorithm is presented and employed for the fast generation of meshless node distributions over arbitrary 3D domains defined by using the stereolithography (STL) file format. The algorithm is based on the node-repel approach where nodes move according to the mutual repulsion of the neighboring nodes. The iterative node-repel approach is coupled with an octree-based technique for the efficient projection of the nodes on the external surface in order to constrain the node distribution inside the domain. Several tests are carried out on three different mechanical components of practical engineering interest and characterized by complexity of their geometry. The generated node distributions are then employed to solve a steady-state heat conduction test problem by using the Radial Basis Function-generated Finite Differences (RBF-FD) meshless method. Excellent results are obtained in terms of both quality of the generated node distributions and accuracy of the numerical solutions
Numerical Simulation of Time-dependent Mixed Convection in a Horizontal Rectangular Channel
No full textInfluence of grid type and turbulence models on the numerical prediction of the flow around marine propellers working in uniform inflow
No full textIn this work we analyze the influence of grid type and turbulence model on the numerical prediction of the flow around marine propellers, working in uniform inflow. The study is carried out comparing hexa-structured meshes with hybrid-unstructured meshes using the SST (Shear Stress Transport) turbulence model and the BSL-RSM (Baseline-Reynolds Stress Model) turbulence model.
The simulations are carried out with a commercial CFD solver. The numerical results are compared with the available experimental data of two propellers in model scale. The comparison is carried out evaluating the global field values, represented by the thrust and torque coefficients, and also considering some local field values measured in the propeller wake. The computational results suggest that, for the numerical predictions of the propeller open water propulsion characteristics, the hexa-structured and
hybrid-unstructured meshes can guarantee similar levels of accuracy. Nevertheless hybrid-unstructured meshes seem to exhibit a more diffusive character than hexa-structured meshes, and thus they are less suited for detailed investigations of the flow field.
Finally, the two different turbulence models behave similarly on both types of meshes, with the BSL-RSM turbulence model providing only slightly better predictions than the computationally more economical SST turbulence model
On the effective thermal conductivity of metal foams
No full textKnowing the effective thermal conductivity is essential in order to design a metal foam heat transfer device. Beside the experimental characterization tests, this quantity can be deduced from empirical correlations and theoretical models. Moreover, CFD (Computational Fluid Dynamics) and numerical modeling in general, at the pore scale, are becoming a promising alternative, especially when coupled with a realistic description of the foam structure, which can be recovered from X-ray computed microtomography (μ-CT). In this work, a review of the most relevant correlations and models published in the literature, usable for the estimation of the effective thermal conductivity of metal foams, will be outlined. In addition, a validation of the models with the experimental values available in the literature will be presented, for both air and water as working fluids. Furthermore, the results of a strategy based on μ-CT – CFD coupling at the pore level will be illustrated
- …
