The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

We examine the scaling law $B \propto M^{\alpha}$ which connects organismal metabolic rate $B$ with organismal mass $M$, where $\alpha$ is commonly held to be 3/4. Since simple dimensional analysis suggests $\alpha=2/3$, we consider this to be a null hypothesis testable by empirical studies. We re-analyze data sets for mammals and birds compiled by Heusner, Bennett and Harvey, Bartels, Hemmingsen, Brody, and Kleiber, and find little evidence for rejecting $\alpha=2/3$ in favor of $\alpha=3/4$. For mammals, we find a possible breakdown in scaling for larger masses reflected in a systematic increase in $\alpha$. We also review theoretical justifications of $\alpha=3/4$ based on dimensional analysis, nutrient-supply networks, and four-dimensional biology. We find that present theories for $\alpha=3/4$ require assumptions that render them unconvincing for rejecting the null hypothesis that $\alpha=2/3$.

https://arxiv.org/pdf/physics/0007096.pdf

Re-examination of the "3/4-law" of Metabolism

Thermal conductivity enhancement on phase change materials for thermal energy storage: A review

Electronic cigarettes (e-cigarettes) are alternative, non-combustible tobacco products that generate an inhalable aerosol containing nicotine, flavors, propylene glycol, and vegetable glycerin. Vaping is now a multibillion dollar industry that appeals to current smokers, former smokers, and young people who have never smoked. E-cigarettes reached the market without either extensive preclinical toxicology testing or long term safety trials that would be required of conventional therapeutics or medical devices. Their effectiveness as a smoking cessation intervention, their impact at a population level, and whether they are less harmful than combustible tobacco products are highly controversial. Here, we review the evidence on the effects of e-cigarettes on respiratory health. Studies show measurable adverse biologic effects on organ and cellular health in humans, in animals, and in vitro. The effects of e-cigarettes have similarities to and important differences from those of cigarettes. Decades of chronic smoking are needed for development of lung diseases such as lung cancer or chronic obstructive pulmonary disease, so the population effects of e-cigarette use may not be apparent until the middle of this century. We conclude that current knowledge of these effects is insufficient to determine whether the respiratory health effects of e-cigarette are less than those of combustible tobacco products.

https://www.bmj.com/content/bmj/366/bmj.l5275.full.pdf

What are the respiratory effects of e-cigarettes?

Nanoparticle filtration by electrospun polymer fibers

Performance evaluation of three optical particle counters with an efficient “multimodal” calibration method

The sizing accuracies of two widely used yet hitherto unevaluated optical particle counters (OPCs—Grimm Model 1.109 and Palas Model WELAS 2100) as well as one high-resolution, non-commercial OPC were evaluated. The measured data were compared to scattering intensity calculations based on Mie theory. Additionally, the counting efficiency for all three counters was measured, as was the influence of coincidence effects for the OPC with the lowest (manufacturer specified) upper concentration limit. Beside the traditional polystyrene latex calibration, a little-known, very fast and precise “multimodal” calibration method was used, which is based on the simultaneous generation of up to eight sharp multiple-charge modes from polydisperse di-ethyl-hexyl-sebacate (DEHS) particles by electrical mobility classification.

Performance evaluation of three optical particle counters with an efficient "multimodal" calibration method

Electronic cigarette usage is increasing worldwide, yet there is a paucity of information on the respiratory health effects of electronic cigarette aerosol exposure. This study aimed to assess whet...

The effects of electronic cigarette aerosol exposure on inflammation and lung function in mice

The well-known phenomena of Plateau–Rayleigh instability has been simulated using computational fluid dynamics (CFD). The breakup of a liquid film into an array of droplets on a cylindrical element was simulated using a volume-of-fluid (VOF) solver and compared to experimental observations and existing theory. It is demonstrated that the VOF method can correctly predict the breakup of thins films into an array of either axisymmetric droplets or clam-shell droplets, depending on the surface energy. The existence of unrealistically large films is precluded. Droplet spacing was found to show reasonable agreement with theory. Droplet motion and displacement under fluid flow was also examined and compared to that in previous studies. It was found that the presence of air flow around the droplet does not influence the stable film thickness; however, it reduces the time required for droplet formation. Novel relationships for droplet displacement were derived from the results.

Plateau Rayleigh Instability Simulation

The current work examines the filtration of both charged and uncharged NaCl nanoparticles in the size range of 2.5–20 nm on grounded metal filters and meshes, and on plastic mesh. The methodology thus allows electrostatic and other effects to be differentiated from true thermal rebound effects (Wang and Kasper 1991). The work also compares measurements under identical conditions made with a number of different condensation particle counters, and a number of different experimental methodologies, in order to allow exclusion of certain measurement errors from the results. It was found that even for particle sizes as small as 2.5 nm there was no measurable deviation from the classical single-fiber-efficiency theory. This conflicts with recently published work (Balazy et al. 2004) which claimed that the thermal bounce of nanometer sized aerosol particles begins to occur at a much larger particle size than previously thought. However, peculiarities or artifacts in CPC counting efficiency at small particle sizes...

Benjamin J. Mullins

Papers

Performance evaluation of three optical particle counters with an efficient “multimodal” calibration method

Performance evaluation of three optical particle counters with an efficient "multimodal" calibration method

The effects of electronic cigarette aerosol exposure on inflammation and lung function in mice

Plateau Rayleigh Instability Simulation

Filtration Efficiency of Aerosol Particles Below 20 Nanometers