Topical Collection "Feature Paper for Mathematical and Computational Fluid Mechanics"

A topical collection in Fluids (ISSN 2311-5521). This collection belongs to the section "Mathematical and Computational Fluid Mechanics".

Editors

Prof. Dr. Laura A. Miller
E-Mail Website
Guest Editor
Departments of Biology and Mathematics, University of North Carolina, Chapel Hill, NC 27599, USA
Interests: mathematical biology, computational fluid dynamics, biomechanics
Special Issues, Collections and Topics in MDPI journals
Dr. Nicholas Battista
E-Mail Website
Guest Editor
Department of Mathematics and Statistics, 2000 Pennington Road, The College of New Jersey, Ewing Township, NJ 08628, USA
Interests: biological fluid dynamics; biological propulsion; teaching computational fluid dynamics; immersed boundary method; fluid-structure interaction
Dr. Amy Buchmann
E-Mail Website
Guest Editor
Department of Mathematics, University of San Diego, 5998 Alcalá Park, San Diego, CA 92110, USA
Interests: computational fluid dynamics; biofluids; Stokes flow Thank you.
Dr. Antonis Anastasiou
E-Mail Website
Guest Editor
Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
Interests: microfluidics; biomaterials; biomedical engineering; multifunctional medical devices; tissue engineering; lasers in the restoration of hard tissues
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

This topical collection features leading research on theoretical and computational studies of problems in fundamental and applied fluid mechanics. Waivers or discounts on article processing charges (APC) will be granted to high-quality papers submitted to this collection. The main aims of this topical collection are (1) to highlight recent advances using mathematical modeling, applied analysis, and numerical simulations to answer problems in modern fluid dynamics, and (2) to disseminate new theoretical and computational frameworks for fluids. We welcome original research papers, reviews, communications, short communications, code release papers, educational papers, and opinions.

Possible topics include, but are not limited to, the following:

  • Novel mathematical models for understanding contemporary fluid mechanic problems in the life sciences, oceanography, geophysics, magneto-fluid dynamics, astrophysics, and other scientific disciplines;
  • New numerical methods for solving the equations of fluid motion, fluid-structure interaction problems, interfacial flows, etc.;
  • New applications of numerical simulations to understand fluid phenomena, particularly those of relevance to microfluidics, medicine, geophysical fluid dynamics, bioinspired design, and astrophysics;
  • The mathematical analysis of the equations of fluid motion, including the use of perturbation techniques to obtain asymptotic solutions for problems relevant to fundamental and applied fluid dynamics;
  • The use of machine learning in computational fluid dynamics.

Prof. Dr. Laura A. Miller
Dr. Nicholas Battista
Dr. Amy Buchmann
Dr. Antonis Anastasiou
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fluids is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (6 papers)

2021

Article
Proposal of a Mask and Its Performance Analysis with CFD for an Enhanced Aerodynamic Geometry That Facilitates Filtering and Breathing against COVID-19
Fluids 2021, 6(11), 408; https://doi.org/10.3390/fluids6110408 - 10 Nov 2021
Viewed by 305
Abstract
As a result of the recent events associated with the SARS-CoV-2 around the world, there has been a need for research to strengthen health care. The use of masks or respirators has been an effective measure, reducing the risk of contagion caused by [...] Read more.
As a result of the recent events associated with the SARS-CoV-2 around the world, there has been a need for research to strengthen health care. The use of masks or respirators has been an effective measure, reducing the risk of contagion caused by the spread of the virus in public places. Currently, there are masks that retain up to 99% of particles >0.3 microns; however, they lack an airtight seal with the face, leading to discomfort and poor protection in conditions without social distancing and areas without ventilation. The device proposed in this study includes a geometric design of static valves with convergent spirals and interior baffles that promotes enhanced aerodynamics with bidirectional flow. According to the analysis and CFD simulation of the proposed reusable, washable, and economic mask and valve system for breathing, coughing, and sneezing events, enhanced air exchange could be maintained, facilitating a higher inhalation flow through the side of the mask (62%) and a higher exhalation through the front of the mask (74%), thereby avoiding the recirculation of the flow to the interior of the mask. The inclusion of filters with KN95 characteristics in the inlets and outlets maintains velocities below 10 cm/s, reducing the probability of infection. Full article
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Tutorial
A CFD Tutorial in Julia: Introduction to Compressible Laminar Boundary-Layer Flows
Fluids 2021, 6(11), 400; https://doi.org/10.3390/fluids6110400 - 05 Nov 2021
Viewed by 313
Abstract
A boundary-layer is a thin fluid layer near a solid surface, and viscous effects dominate it. The laminar boundary-layer calculations appear in many aerodynamics problems, including skin friction drag, flow separation, and aerodynamic heating. A student must understand the flow physics and the [...] Read more.
A boundary-layer is a thin fluid layer near a solid surface, and viscous effects dominate it. The laminar boundary-layer calculations appear in many aerodynamics problems, including skin friction drag, flow separation, and aerodynamic heating. A student must understand the flow physics and the numerical implementation to conduct successful simulations in advanced undergraduate- and graduate-level fluid dynamics/aerodynamics courses. Numerical simulations require writing computer codes. Therefore, choosing a fast and user-friendly programming language is essential to reduce code development and simulation times. Julia is a new programming language that combines performance and productivity. The present study derived the compressible Blasius equations from Navier–Stokes equations and numerically solved the resulting equations using the Julia programming language. The fourth-order Runge–Kutta method is used for the numerical discretization, and Newton’s iteration method is employed to calculate the missing boundary condition. In addition, Burgers’, heat, and compressible Blasius equations are solved both in Julia and MATLAB. The runtime comparison showed that Julia with for loops is 2.5 to 120 times faster than MATLAB. We also released the Julia codes on our GitHub page to shorten the learning curve for interested readers. Full article
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Article
Fluid Dynamics in Curvilinear Coordinates without Fictitious Forces
Fluids 2021, 6(10), 366; https://doi.org/10.3390/fluids6100366 - 16 Oct 2021
Viewed by 274
Abstract
The use of curvilinear coordinates is sometimes indicated by the inherent geometry of a fluid dynamics problem, but this introduces fictitious forces into the momentum equations that spoil the strict conservative form. If one is willing to work in three dimensions, these fictitious [...] Read more.
The use of curvilinear coordinates is sometimes indicated by the inherent geometry of a fluid dynamics problem, but this introduces fictitious forces into the momentum equations that spoil the strict conservative form. If one is willing to work in three dimensions, these fictitious forces can be eliminated by solving for rectangular (Cartesian) momentum components on a curvilinear mesh. A thoroughly geometric approach to fluid dynamics on spacetime demonstrates this transparently, while also giving insight into a greater unity of the relativistic and nonrelativistic cases than is usually appreciated. Full article
Article
Improvement of a Diagnostic Urban Wind Model for Flow Fields around a Single Rectangular Obstacle in Micrometeorology Simulation
Fluids 2021, 6(7), 254; https://doi.org/10.3390/fluids6070254 - 12 Jul 2021
Viewed by 498
Abstract
In general, computational fluid dynamics (CFD) models incur high computational costs when dealing with realistic and complicated flows. In contrast, the mass-consistent flow (MASCON) field model provides a three-dimensional flow field at reasonable computational cost. Unfortunately, some weaknesses in simulating the flow of [...] Read more.
In general, computational fluid dynamics (CFD) models incur high computational costs when dealing with realistic and complicated flows. In contrast, the mass-consistent flow (MASCON) field model provides a three-dimensional flow field at reasonable computational cost. Unfortunately, some weaknesses in simulating the flow of the wake zone exist because the momentum equations are not considered in the MASCON field model. In the present study, a new set of improved algebraic models to provide initial flow fields for the MASCON field model are proposed to overcome these weaknesses by considering the effect of momentum diffusion in the wake zone. Specifically, these models for the wake region are developed on the basis of the wake models used in well-recognized Gaussian plume models, ADMS-build and PRIME. The MASCON fields provided by the new set of wake zone models are evaluated against wind-tunnel experimental data on flow around a wall-mounted rectangular obstacle. Each MASCON field is compared with the experimental results, focusing on the positions of the vortex core and saddle points of the vortex formed in the near-wake zone and the vertical velocity distribution in the far-wake zone. The set of wake zone models developed in the present study better reproduce the experimental results in both the wake zones compared to the previously proposed models. In particular, the complicated recirculation flow which is formed by the union of the sidewall recirculation zone and the near-wake zone is reproduced by the present wake zone model using the PRIME model that includes the parameterization of the sidewall recirculation zones. Full article
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Article
Hydrodynamic Entrance Length for Laminar Flow in Microchannels with Rectangular Cross Section
Fluids 2021, 6(7), 240; https://doi.org/10.3390/fluids6070240 - 01 Jul 2021
Viewed by 696
Abstract
This work presents a detailed numerical investigation on the required development length (L=L/B) in laminar Newtonian fluid flow in microchannels with rectangular cross section and different aspect ratios (AR). The advent of new microfluidic [...] Read more.
This work presents a detailed numerical investigation on the required development length (L=L/B) in laminar Newtonian fluid flow in microchannels with rectangular cross section and different aspect ratios (AR). The advent of new microfluidic technologies shifted the practical Reynolds numbers (Re) to the range of unitary (and even lower) orders of magnitude, i.e., creeping flow conditions. Therefore, accurate estimations of L at ReO(1) are important for microsystem design. At such low Reynolds numbers, in which inertial forces are less dominant than viscous forces, flow characteristics become necessarily different from those at the macroscale where Re is typically much larger. A judicious choice of mesh refinement and adequate numerical methods allowed obtaining accurate results and a general correlation for estimating L, valid in the ranges 0Re2000 and 0.1AR1, thus covering applications in both macro and microfluidics. Full article
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Article
Analysis of the Thermal Behavior of a New Structure of Protected Agriculture Established in a Region of Tropical Climate Conditions
Fluids 2021, 6(6), 223; https://doi.org/10.3390/fluids6060223 - 14 Jun 2021
Cited by 2 | Viewed by 700
Abstract
Determining airflow patterns and their effect on the distribution of microclimate variables such as temperature is one of the most important activities in naturally ventilated protected agricultural structures. In tropical countries, this information is used by farmers and decision makers when defining climate [...] Read more.
Determining airflow patterns and their effect on the distribution of microclimate variables such as temperature is one of the most important activities in naturally ventilated protected agricultural structures. In tropical countries, this information is used by farmers and decision makers when defining climate management strategies and for crop-specific cultural work. The objective of this research was to implement a validated Computational Fluid Dynamics (CFD) model in 3D to determine the aerodynamic and thermal behavior of a new protected agricultural structure established in a warm climate region in the Dominican Republic. The numerical evaluation of the structure was carried out for the hours of the daytime period (6–17 h), the results found allowed to define that the CFD model generates satisfactory predictions of the variables evaluated. Additionally, it was found that airflow patterns are strongly affected by the presence of porous insect screens, which generate moderate velocity flows (<0.73 m s−1) inside the structure. It was also identified that the value of the average temperature inside the structure is directly related to the air flows, the level of radiation and the temperature of the outside environment. Full article
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