International Journal for Numerical Methods in Fluids

Tufillaro, Nicholas; Williams, David M.; Nishikawa, Hiroaki

doi: 10.1002/fld.70084pmid: N/A

Many time‐dependent problems in the field of computational fluid dynamics (CFD) can be solved using space‐time methods. However, such methods can encounter issues with computational cost and robustness. To address these issues, efficient, node‐centered edge‐based schemes are currently being developed. In these schemes, a median‐dual tessellation of the space‐time domain is constructed based on an initial triangulation. These methods are node‐centered or node‐based, as the primary components of the discretization are median‐dual regions (polytopes) that surround the mesh nodes. These methods are extremely robust, as the median‐dual regions will often maintain a positive volume and other good geometric properties, even in cases when some of the associated simplices have negative volumes, or other poor geometric properties. Unfortunately, it is not straightforward to construct median‐dual regions or deduce their properties on triangulations for d≥3$$ d\ge 3 $$. In this work, we provide the first rigorous definition of median‐dual regions on triangulations in any number of dimensions. In addition, we introduce a new method for computing the hypervolume of a median‐dual region in ℝd$$ {\mathbb{R}}^d $$. Furthermore, we provide a new approach for computing the directed‐hyperarea vectors for faces of a median‐dual region in ℝ4$$ {\mathbb{R}}^4 $$. These geometric properties are key for developing node‐centered edge‐based schemes in any number of dimensions. We conclude our work by analyzing the computational complexity of the edge‐based schemes, and performing numerical experiments in two, three, and four dimensions. We successfully demonstrate their effectiveness by obtaining accurate solutions to several canonical problems.

Liu, Zongyuan; Li, Jiajie; Zhu, Shengfeng

doi: 10.1002/fld.70083pmid: N/A

We investigate multi‐physical topology optimization for microfluidic mixers. Starting from the Ising model, we derive a thermodynamically consistent Ginzburg–Landau free energy functional that incorporates the objective functional as an effective external field, providing a physically interpretable framework for phase‐field topology optimization. To eliminate fluid blockage in microfluidic mixers, we incorporate the coupled Navier–Stokes, convection–diffusion, and Poisson–Boltzmann equations. An Allen–Cahn type gradient flow method is proposed based on sensitivity analysis. The algorithm is validated for its computational effectiveness through numerical simulations of benchmark problems in 2D and 3D.