Causal heat transport induced by zeptosecond laser pulses

This article is devoted to the problem of thermal convection in porous media with volumetric heat generation modelling, arising in practice of radioactive waste (RW) disposal safety assessment. In the first section a brief overview of widespread hydrogeological codes (FEFLOW, SUTRA, SEAWAT, TOUGH2) featuring the ability to solve thermal problems is done. We point out the lack of heat generation caused by radioactive decay model in these programs. The GeRa numerical code developed by the authors is presented. In the second section we consider the mathematical model of coupled groundwater flow, solute and heat transport, which is implemented in GeRa. The model describes these processes in saturated porous media and takes into account radioactive decay, sorption on the rock, the dependences of density and viscosity on temperature. The heat transport equation is written assuming thermal equilibrium between the fluid and the rock. The model includes heat transport by convection and conduction-thermal dispersion. The heat source terms can be wells and volumetric heat generation due to radioactive decay. The numerical scheme implemented in GeRa to solve the aforementioned coupled problem is introduced in the third section. The space discretization is done using finite volume methods (FVM). Sequential iterative coupling implicit scheme is used for temporal discretization. On each iteration of the scheme the flow, heat transport and solute transport problems are solved sequentially. The fourth section is devoted to the test problem of heat generating fluid convection in a closed two- dimensional cavern filled by porous material with isothermal walls. The results obtained using GeRa code are compared to the asymptotical solution deduced by Haajizadeh. In the fifth section we present the results of modelling with GeRa the experiments of Buretta and Berman in which they investigated the regimes of free thermal convection of fluid with volumetric heat generation in porous media. The dependences of Nusselt number on the Raley number measured in the experiments and calculated numerically are compared. In the sixth section we consider the test problem of continuous injection of high-level RW into an aquifer. Here the ability to model coupled flow, heat and solute transport processes is shown. The numerical solution obtained using GeRa is compared to a known analytical one.

The cotton-based composite is equipped with a single/double semipermeable membrane made of polyurethane (PU) (100%), which blocks liquid transport to the surrounding environment. The complex problem analyzed involves the coupled transport of water vapor within the textile material, transport of liquid water in capillaries, as well as heat transport with vapor and liquid water. The problem can be described using the mass transport equation for water vapor, heat transport equation, and mass transport equation for liquid moisture, accompanied by the set of corresponding boundary and initial conditions. State variables are determined using a complex multistage solution procedure within the selected points for each layer. The distributions of state variables are determined for different configurations of membranes.

Modeling water stable isotope transport in soil is crucial to sharpen our understanding of water cycles in terrestrial ecosystems. Although several models for soil water isotope transport have been developed, many rely on a semi‐coupled numerical approach, solving isotope transport only after obtaining solutions from water and heat transport equations. However, this approach may increase instability and errors of model. Here, we developed an algorithm that solves one‐dimensional water, heat, and isotope transport equations with a fully coupled method (MOIST). Our results showed that MOIST is more stable under various spatial and temporal discretization than semi‐coupled method and has good agreement with semi‐analytical solutions of isotope transport. We also validated MOIST with long‐term measurements from a lysimeter study under three scenarios with soil hydraulic parameters calibrated by HYDRUS‐1D in the first two scenarios and by MOIST in the last scenario. In scenario 1, MOIST showed an overall NSE , KGE , and MAE of simulated δ 18 O of 0.47, 0.58, and 0.92‰, respectively, compared to the 0.31, 0.60, and 1.00‰ from HYDRUS‐1D; In scenario 2, these indices of MOIST were 0.33, 0.52, and 1.04‰, respectively, compared to the 0.19, 0.58, and 1.15‰ from HYDRUS‐1D; In scenario 3, calibrated MOIST exhibited the highest NSE (0.48) and KGE (0.76), the smallest MAE (0.90) among all scenarios. These findings indicate MOIST has better performance in simulating water flow and isotope transport in simplified ecosystems than HYDRUS‐1D, suggesting the great potential of MOIST in furthering our understandings of ecohydrological processes in terrestrial ecosystems.

The correspondence between the eigenfunctions of the Modified Schrodinger Equation (M.S.E.) for the hydrogen molecule and the symmetrized eigenfunctions of the ordinary Schrodinger equation is discussed, together with the role played by the arbitrary parameter appearing in the M.S.E. Hamiltonian. A nonempirical criterion is given for determining the best value of such a parameter.

The discrete element method (DEM) can be used for modeling moving granular media in which heat and mass transport takes place. In this paper the concept of discrete element modeling with special emphasize on applicable force laws is introduced and the necessary equations for heat transport within particle assemblies are derived. Possible flow regimes in moving granular media are discussed. The developed discrete element model is applied to a new staged reforming process for biomass and waste utilization which employs a solid heat carrier. Results are presented for the flow regime and heat transport in substantial vessels of the process.

The discrete element method can be used for modeling moving granular media in which heat and mass transport takes place. In this paper the concept of discrete element modeling with special emphasis on applicable force laws is introduced and the necessary equations for heat transport within particle assemblies are derived. Possible flow regimes in moving granular media are discussed. The developed discrete element model is applied to a new staged reforming process for biomass and waste utilization which employs a solid heat carrier. Results are presented for the flow regime and heat transport in substantial vessels of the process.

A mathematical model of a solar air thermosyphon integrated with building envelope

Consciousness comes out of quantum mechanics — from the presence of tunneling in the brain, and from state vector collapse brought on by the brain’s comparison loops. This fact is tied to the machinery of the MSE — the modified Schrodinger equation. This understanding of consciousness also lets us resolve problems in neurophysiology and even in physics — the resolution of the disparity that has long beset general relativity vis a vis quantum theory. We use this understanding of consciousness as a quantum process to resolve the measurement problem in quantum mechanics and to obtain quantities that allow us to test experimentally the viability of this theory.

Fuel cells are electrochemical devices that directly transform chemical energy into electricity, which are promising for future energy systems, since they are energy efficient and, when hydrogen is used as fuel, there are no direct emissions of greenhouse gases. The cell performance depends strongly on the material characteristics, the operating conditions and the chemical reactions that occur inside the cell. The chemical- and electrochemical reaction rates depend on temperature, material structure, catalytic activity, degradation and the partial pressures for the different species components. There is a lack of information, within the open literature, concerning the fundamentals behind these reactions. Experimental as well as modeling studies are needed to reduce this gap. In this study experimental data collected from an intermediate temperature standard SOFC with H2/H2O in the fuel stream are used to validate a previously developed computational fluid dynamics model based on the finite element method. The developed model is based on the governing equations of heat and mass transport and fluid flow, which are solved together with kinetic expressions for internal reforming reactions of hydrocarbon fuels and electrochemistry. This model is further updated to describe the experimental environment concerning cell design. Discussion on available active area for electrochemical reactions and average ionic transport distance from the anodic- to the cathodic three-phase boundary (TPB) are presented. The fuel inlet mole fractions are changed for the validated model to simulate a H2/H2O mixture and 30% pre-reformed natural gas.

Groundwater transport of crater-lake brine at Poa´s Volcano, Costa Rica

Blood transport has many crucial answers and unanswered questions responsible for the formation of metastasis, growth, and effective treatments. In any therapy (radiotherapy, chemotherapy, or immunotherapy), blood carries the required agents, such as oxygen or pharmacological agents. Blood viscosity and concentration are important factors to study. Two-phase biorheology of the blood is considered with chemical reaction and volume fraction. Heat and mass transport are proposed to be studied with the Soret application. The angle of inclination of the applied magnetic field is 0 to 90 degrees. The concentrated agents (drugs) carried by the blood create chemical reactions in the surrounding medium. Thus, the mathematical model is governed by partial differential equations (PDEs) for fluid transport, heat transport, and mass transport. These equations are solved using the mathematical function PDEPE in the software MATLAB. These transport interactions in tumor regions are obtained for fluid velocity, suspension velocity, thermal profiles, and concentration profiles for parameters like Soret number (Sr), volume fraction ( ), magnetic intensity (M), Chemical reaction parameter ( ), thermal radiation parameter (Rd), etc. These results are validated through graphs and tables obtained. Soret effects vary, which reduces transport velocity, which will support drug delivery systems. Thermal parameters on blood flow, heat stress, and concentration that help in tumor treatments are described using numerical outputs and depicted through graphs.

Numerical study of induction heating and heat transfer in a real Czochralski system

Modeling works which simulate the proton-exchange membrane fuel cell with the computational fluid dynamics approach involve the simultaneous solution of multiple, interconnected physics equations for fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts vary by how they treat the physics within and adjacent to the membrane-electrode assembly (MEA). Certain approaches treat the MEA not as part of the computational domain, but rather an interface connecting the anode and cathode computational domains. These approaches may lack the ability to consistently model catalyst layer losses and MEA ohmic resistance. This work presents an upgraded interface formulation where coupled water, heat, and current transport behaviors of the MEA are modeled analytically. Improving upon the previous work, catalyst layer losses can now be modeled accurately without ad-hoc selection of model kinetic parameters. Key to the formulation is the incorporation of water absorption/desorption resistances. The interface model is developed with the consideration of only thru-plane variation, based upon varied fundamental research into each of the relevant physics. The model is validated against differential cell data with high- and low-humidity reactants. The agreement is very good in each case.

The software package VS2DI was developed by the U.S. Geological Survey for simulating water, solute, and heat transport in variably saturated porous media. The package consists of a graphical preprocessor to facilitate construction of a simulation, a postprocessor for visualizing simulation results, and two numerical models that solve for flow and solute transport (VS2DT) and flow and heat transport (VS2DH). The finite‐difference method is used to solve the Richards equation for flow and the advection–dispersion equation for solute or heat transport. This study presents a brief description of the VS2DI package, an overview of the various types of problems that have been addressed with the package, and an analysis of the advantages and limitations of the package. A review of other models and modeling approaches for studying water, solute, and heat transport also is provided.

The area of the 9.1-km-deep Continental Deep Drillhole (KTB) in Germany is used as a case study for a geothermal reservoir situated in folded and faulted metamorphic crystalline crust. The presented approach is based on the analysis of 3-D seismic reflection data combined with borehole data and hydrothermal numerical modelling. The KTB location exemplarily contains all elements that make seismic prospecting in crystalline environment often more difficult than in sedimentary units, basically complicated tectonics and fracturing and low-coherent strata. In a first step major rock units including two known nearly parallel fault zones are identified down to a depth of 12 km. These units form the basis of a gridded 3-D numerical model for investigating temperature and fluid flow. Conductive and advective heat transport takes place mainly in a metamorphic block composed of gneisses and metabasites that show considerable differences in thermal conductivity and heat production. Therefore, in a second step, the structure of this unit is investigated by seismic waveform modelling. The third step of interpretation consists of applying wavenumber filtering and log-Gabor-filtering for locating fractures. Since fracture networks are the major fluid pathways in the crystalline, we associate the fracture density distribution with distributions of relative porosity and permeability that can be calibrated by logging data and forward modelling of the temperature field. The resulting permeability distribution shows values between 10-16 and 10-19 m(-2) and does not correlate with particular rock units. Once thermohydraulic rock properties are attributed to the numerical model, the differential equations for heat and fluid transport in porous media are solved numerically based on a finite difference approach. The hydraulic potential caused by topography and a heat flux of 54 mW m(-2) were applied as boundary conditions at the top and bottom of the model. Fluid flow is generally slow and mainly occurring within the two fault zones. Thus, our model confirms the previous finding that diffusive heat transport is the dominant process at the KTB site. Fitting the observed temperature-depth profile requires a correction for palaeoclimate of about 4 K at 1 km depth. Modelled and observed temperature data fit well within 0.2 degrees C bounds. Whereas thermal conditions are suitable for geothermal energy production, hydraulic conditions are unfavourable without engineered stimulation.