scholarly journals Cavitation in Pharmaceutical Manufacturing

2020 ◽  
Author(s):  
Donn Sederstrom ◽  
Rafael Valotta Rodrigues ◽  
Corinne Lengsfeld
Keyword(s):  
Fluid Dynamic ◽  
Particle Formation ◽  
Pharmaceutical Manufacturing ◽  
Product Recalls ◽  
Dynamic Simulations ◽  
Visible Particle ◽  
Threshold Criterion ◽  
Fluid Properties ◽  
Processing Steps ◽  
Research Show

Therapeutic proteins are used to successfully treat hemophilia, Crohn’s Disease, diabetes, and cancer. Recent product recalls have occurred because of sub-visible particle formation resulting from the inherent instability of proteins. It has been suggested that particle formation is associated with late stage processing steps of filling, shipping, and delivery. Previous works demonstrated that cavitation might occur in therapeutic vials subjected to agitation or accidentally dropped, but that mitigation can be achieved with fluid property manipulation. The goal of this research was to (1) assess the risk of cavitation under common pharmaceutical manufacturing conditions (i.e., pipe contraction and pumps), (2) establish a simple threshold criterion for when particulate will form, and (3) suggest a series of mitigation techniques based on these thresholds. To accomplish these tasks, computational fluid dynamic simulations for a variety of pipe contraction and fluid properties were performed. The results of this research show that reducing the turbulence in a fluid system will reduce the likelihood of cavitation. Additionally, threshold bounds were created that establish a definitive transition at which cavitation will occur.

Towards real-time fire data synthesis using numerical simulations

2021 ◽  
pp. 073490412199344
Author(s):  
Wolfram Jahn ◽  
Frane Sazunic ◽  
Carlos Sing-Long
Keyword(s):  
Real Time ◽  
Computational Fluid Dynamic ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Near Field ◽  
Computing Time ◽  
Temperature Correction ◽  
Dynamic Simulations ◽  
Conservation Of Energy ◽  
Fire Scenarios

Synthesising data from fire scenarios using fire simulations requires iterative running of these simulations. For real-time synthesising, faster-than-real-time simulations are thus necessary. In this article, different model types are assessed according to their complexity to determine the trade-off between the accuracy of the output and the required computing time. A threshold grid size for real-time computational fluid dynamic simulations is identified, and the implications of simplifying existing field fire models by turning off sub-models are assessed. In addition, a temperature correction for two zone models based on the conservation of energy of the hot layer is introduced, to account for spatial variations of temperature in the near field of the fire. The main conclusions are that real-time fire simulations with spatial resolution are possible and that it is not necessary to solve all fine-scale physics to reproduce temperature measurements accurately. There remains, however, a gap in performance between computational fluid dynamic models and zone models that must be explored to achieve faster-than-real-time fire simulations.

scholarly journals Analysis of Radial Inflow Turbine Losses Operating with Supercritical Carbon Dioxide

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3561
Author(s):  
Antti Uusitalo ◽  
Aki Grönman
Keyword(s):  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Average Deviation ◽  
Loss Analysis ◽  
Specific Speed ◽  
Loss Models ◽  
Rotor Losses ◽  
Radial Turbines ◽  
Design Power ◽  
Good Agreement

The losses of supercritical CO2 radial turbines with design power scales of about 1 MW were investigated by using computational fluid dynamic simulations. The simulation results were compared with loss predictions from enthalpy loss correlations. The aim of the study was to investigate how the expansion losses are divided between the stator and rotor as well as to compare the loss predictions obtained with the different methods for turbine designs with varying specific speeds. It was observed that a reasonably good agreement between the 1D loss correlations and computational fluid dynamics results can be obtained by using a suitable set of loss correlations. The use of different passage loss models led to high deviations in the predicted rotor losses, especially with turbine designs having the highest or lowest specific speeds. The best agreement in respect to CFD results with the average deviation of less than 10% was found when using the CETI passage loss model. In addition, the other investigated passage loss models provided relatively good agreement for some of the analyzed turbine designs, but the deviations were higher when considering the full specific speed range that was investigated. The stator loss analysis revealed that despite some differences in the predicted losses between the methods, a similar trend in the development of the losses was observed as the turbine specific speed was changed.

Computational fluid dynamic simulations of coal-fired utility boilers: An engineering tool

Fuel ◽  
2009 ◽  
Vol 88 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Efim Korytnyi ◽  
Roman Saveliev ◽  
Miron Perelman ◽  
Boris Chudnovsky ◽  
Ezra Bar-Ziv
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Utility Boilers

scholarly journals Tests of the sorption and olfactory “fovea” hypotheses in the mouse

2017 ◽  
Vol 118 (5) ◽  
pp. 2770-2788 ◽  
Author(s):  
David M. Coppola ◽  
Brittaney E. Ritchie ◽  
Brent A. Craven
Keyword(s):  
Olfactory Epithelium ◽  
Water Solubility ◽  
Fluid Dynamic ◽  
Water Soluble ◽  
Quiet Breathing ◽  
Cfd Simulations ◽  
Dynamic Simulations ◽  
Consistent Finding ◽  
Sensory Epithelia ◽  
Tactile Stimuli

The spatial distribution of receptors within sensory epithelia (e.g., retina and skin) is often markedly nonuniform to gain efficiency in information capture and neural processing. By contrast, odors, unlike visual and tactile stimuli, have no obvious spatial dimension. What need then could there be for either nearest-neighbor relationships or nonuniform distributions of receptor cells in the olfactory epithelium (OE)? Adrian (Adrian ED. J Physiol 100: 459–473, 1942; Adrian ED. Br Med Bull 6: 330–332, 1950) provided the only widely debated answer to this question when he posited that the physical properties of odors, such as volatility and water solubility, determine a spatial pattern of stimulation across the OE that could aid odor discrimination. Unfortunately, despite its longevity, few critical tests of the “sorption hypothesis” exist. Here we test the predictions of this hypothesis by mapping mouse OE responses using the electroolfactogram (EOG) and comparing these response “maps” to computational fluid dynamics (CFD) simulations of airflow and odorant sorption patterns in the nasal cavity. CFD simulations were performed for airflow rates corresponding to quiet breathing and sniffing. Consistent with predictions of the sorption hypothesis, water-soluble odorants tended to evoke larger EOG responses in the central portion of the OE than the peripheral portion. However, sorption simulation patterns along individual nasal turbinates for particular odorants did not correlate with their EOG response gradients. Indeed, the most consistent finding was a rostral-greater to caudal-lesser response gradient for all the odorants tested that is unexplained by sorption patterns. The viability of the sorption and related olfactory “fovea” hypotheses are discussed in light of these findings. NEW & NOTEWORTHY Two classical ideas concerning olfaction’s receptor-surface two-dimensional organization—the sorption and olfactory fovea hypotheses—were found wanting in this study that afforded unprecedented comparisons between electrophysiological recordings in the mouse olfactory epithelium and computational fluid dynamic simulations of nasal airflow. Alternatively, it is proposed that the olfactory receptor layouts in macrosmatic mammals may be an evolutionary contingent state devoid of the functional significance found in other sensory epithelia like the cochlea and retina.

scholarly journals Numerical study of hydrogen mild combustion

2009 ◽  
Vol 13 (3) ◽  
pp. 59-67 ◽  
Author(s):  
Enrico Mollica ◽  
Eugenio Giacomazzi ◽  
Marco di
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Thermal Gradients ◽  
Radiation Model ◽  
Dynamic Simulations ◽  
Mild Combustion ◽  
Preheating Temperature ◽  
Nitric Oxide Emissions ◽  
Gas Recirculation ◽  
Good Agreement

In this article a combustor burning hydrogen and air in mild regime is numerically studied by means of computational fluid dynamic simulations. All the numerical results show a good agreement with experimental data. It is seen that the flow configuration is characterized by strong exhaust gas recirculation with high air preheating temperature. As a consequence, the reaction zone is found to be characteristically broad and the temperature and concentrations fields are sufficiently homogeneous and uniform, leading to a strong abatement of nitric oxide emissions. It is also observed that the reduction of thermal gradients is achieved mainly through the extension of combustion in the whole volume of the combustion chamber, so that a flame front no longer exists ('flameless oxidation'). The effect of preheating, further dilution provided by inner recirculation and of radiation model for the present hydrogen/air mild burner are analyzed.

Study of Air Inclusion in Lubrication System of CVT Gearbox Transmission With Biphasic CFD Simulation

2016 ◽  
Author(s):  
Cristian Ferrari ◽  
Pietro Marani
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Critical Conditions ◽  
Positive Pressure ◽  
Computational Domain ◽  
Lubrication System ◽  
Operation Condition ◽  
Dynamic Simulations ◽  
Lubrication Performance ◽  
Lumped Element Model

The focus of this paper is the biphasic phenomena that occurs in a lubrication system of a CVT gearbox transmission of an agricultural tractor, in particular a Method of Analysis is outlined with the aim of mapping and assessing the behavior of the lubrication circuit. The study of the lubrication in gearboxes is an important issue in the design of off-road machines because their reliability depends mostly on the lubrication performance, as well as the machine’s lifetime and overall energy efficiency of the transmission is strongly dependent on the lubrication system behavior. In fact the role of the lubrication system is twofold: firstly to remove the heat generated in the highly loaded rolling bearings and the gears found in the power and accessory gearboxes via heat exchangers; secondly to lubricate these parts. The trend in the development of gearbox transmissions has been towards lower consumption and higher power transmitted, consequently it is necessary to conceive more effective and efficient lubrication systems. Nonetheless the lubrication problem often relies on a trial and error approach and most available scientific literature is based on lumped element model dynamic simulation or one phase thermo-fluid dynamic simulations, overlooking the effects linked to cavitation and air inclusion. One important phenomenon in lubrication systems is that of air suction. This can be seen in particular at high rotational speeds of shafts when the centrifugal force causes a positive pressure drop between inner lubrication pipes and outer radial conduits. In this case the air occupies part of the lubrication conduits, and since the domain is shared by the outflowing liquid phase and the air included, the monophase CFD simulation fails to predict the correct lubrication flow. If this effect is not carefully considered it could cause a lubrication unbalance among the various parts of the gearbox, creating a risk of transmission damage. In this paper the methodology will be presented step by step until in final a complete map of operation condition is created. A preliminary analysis of the circuitry is an essential phase of the project since the tractor’s transmission is an extremely complex assembly composed by hundreds of components therefore the lubrication circuit appears as a large net of moving hydraulic connections and consumers. From this analysis a computational domain is obtained and appropriately meshed. After the pivotal choice of the proper turbulence model and boundary conditions, various runs at different rotating speeds corresponding to the different operating ranges will be performed. The result will be contextualized by commenting on the fluid dynamics phenomena involved and the influence parameters on flow rate distribution, finally evaluating the performances of the lubrication circuit, and in particular highlighting the most critical conditions in terms of speed condition and locating the most critical gearbox parts.

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