RESUMEN
Surface nanostructure, either designed or generated as an artifact of the fabrication procedure, is known to influence interfacial phenomena intriguingly. While surface roughness-wettability coupling over nanometer scales has been addressed to some extent, the explicit interplay of hydrodynamics and confinement toward dictating the underlying characteristics for practically relevant material interfaces remains unexplored. Here, we bring out unique roles of surface nanostructures toward altering flow of water in a copper nanochannel, by capturing an exclusive interplay of confinement, roughness, wettability and flow dynamics. Toward this, non-equilibrium molecular dynamics (NEMD) simulations are performed to examine the effect of nanoscale triangular roughness. The width and height of the triangular microgroove are varied along with different driving forces at the channel inlet, and the results are compared with those corresponding to smooth-walled nanochannels. We also unveil the nontrivial characteristics of the interfacial topology as a consequence of spontaneous phase separation at the fluid-solid interface. For a constant driving force, we show that the interface may exhibit concave or convex topology, depending on the nanogroove geometry. Our results provide new vistas on how designed nanoscale roughness structures can be harnessed toward controlling the transport of water in a practically engineered nanosystem, as demanded by the specific application on hand.
RESUMEN
The widely used ice chamber-based cold storage for the transportation and storage of vaccines has several disadvantages, including uncontrolled overall temperature, water accumulation, and frequent ice pack renewal. Therefore, in this work, we numerically studied a novel vaccine storage system by coupling magnetic refrigeration and ice packs developed by conserving the advantages of an ice-based system. A two-dimensional numerical model is developed to analyze the magnetohydrodynamic natural convection in the storage chamber. Gadolinium of 0.08 kg is used to produce a cooling power of 31.514 W and a coefficient of performance of 1.3. With the constant heat leaked of 0.828 W into the system with dimensions of (0.1 × 0.1) m, the average life of the ice pack of 0.75 kg is 1.03 h. By introducing the magnetocaloric effect, the life of the same ice pack can be infinite with no load. The dynamic mode decomposition analysis reveals that the most dominant fluid interaction occurs between the cooled gadolinium plate and the adjacent fluid, resulting in efficient cooling of the air chamber. The developed vaccine chamber design will significantly improve the existing ice pack system with a nominal increase in cost and system weight.
RESUMEN
We have performed a three-dimensional numerical simulation to determine the effect of local atmospheric pollution level on the spreading characteristics of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus through ejected droplets during sneezing and coughing in an open space. Utilizing a finite volume-based numerical method, we have performed computations for various ranges of droplet diameters and sneezing speeds. The interactions between the droplets and the suspended particles are considered by taking both hydrophobic and hydrophilic wettability characteristics into account. Our computational results show that the virus-containing droplets partially affect aerosols during the path of their transmission. With the progression of time, the droplet distribution shows an asymmetric pattern. The maximum dispersion of these droplets is found for higher sneezing velocities. The droplets with a diameter of 50 µm travel a larger distance than the larger diameter droplets. We have found that an aerosol with hydrophilic wettability undergoes complete wetting by the disease-containing droplets and therefore is conducive to disease propagation. The droplet engagement duration with aerosol decreases with increase in the sneezing velocity. Our study recommends against using physical exercise centers in a closed environment such as gymnasium and indoor games during the COVID pandemic, especially in a polluted environment. The results from our work will help in deciding proper social distancing guidelines based on the local atmospheric pollution level. They may act as a precursor in controlling further spread of diseases during this unprecedented situation of the COVID pandemic.
RESUMEN
The ongoing global pandemic due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is in the crucial stage. The vaccine is still at the developing stage. Currently, the only way to check the spreading of this virus is self-isolation. It is reported that a good number of health workers are infected while treating patients suffering from COVID 19. Therefore, an effort is made to develop a system that can enhance safety and check unwanted viruses. Although the complete specification of the SARS-CoV-2 is yet to be evaluated, the present work considers the characteristic of SARS-CoV-1, which closely relates to that of SARS-CoV-2. The proteins are one of the most important structural and functional molecules of the virus; therefore, few properties of a protein are considered. In this work, we propose a sanitization procedure of the personal protective equipment (PPE), such as gloves and masks, before and after the use, by employing high voltage charge generator (30 kV) from a very low DC source of 5 V to eliminate the virus from the surface of PPE. The positive output is connected to a metallic surface coated with carbon nanotubes (CNT) or a metallic surface ablated using lithography to achieve desired nano-grooves of 200 nm. At the tip of these nano-grooves, a very high electric field is generated which readily ionises the air in the vicinity of the tip. The high electric field alters the induced dipole of the protein of the virus, causing permanent damage in terms of electroporation. Further positive salt ions diffuse into the protein of the viruses, causing it inactive and disintegrate.
RESUMEN
The early diagnosis of cancer at any location of the human body can help in enhancing the survival rate and in reducing the cost of the treatment. Among the several techniques, the conventional infra-red (IR) thermography suffers from several limitations, including higher patient discomfort and longer time for tumour detection based on the temperature difference between tumour and adjacent healthy tissues. Hence, in this work, a novel non-invasive hot stress dynamic IR thermography system is proposed to detect surface tumour without severe discomfort to the patient. The system is designed to detect the surface tumour under 3 min within a temperature range of 42 and 37 °C. A two-dimensional numerical model based on the bio-heat transfer of tissue consists of cancerous and healthy cells is developed and validated to analysis the thermal contrast arises due to the presence of cancerous and healthy cells while cooling naturally. A light source is introduced with appropriate intensity to achieve a suitable temperature contrast. Moreover, the effects of natural convective heat loss from the tissue to the ambient and the scanning speed of IR Thermography on the tissue are investigated. A temperature difference of about 1.5 °C is found after cooling of tissues for 140 s, which can be detected using a thermographic camera. Finally, a sensitivity study is conducted to access the importance of the individual parameter over the final temperature field. The results predict the blood perfusion rate as the most significant parameter that significantly influences the temperature distribution in the considered domain.