Radiation Reaction Research Articles

Radiation reaction on a charged particle

The radiation reaction on a charged particle in a constant magnetic field is computed in a direct way using the methods of non-equilibrium statistical mechanics namely the subdynamics theory developed in Brussels (Prigogine et al. 1973; Balescu, 1975) associated with a statistical description of the transverse field (Balescu et al. 1974). A dynamical criteria is used such that the virtual (self-energy) processes no longer appear explicitly in the kinetic equation describing the distribution function associated with the particle (de Haan, 2004 [4,5]). That irreversible kinetic equation is then derived in a straightforward way. The response of the charged particle to its own electromagnetic field is then deduced and provides an exponential decay of its transverse momentum with respect to the magnetic field. The usual form for the reactive force is thus recovered in a framework that enables its generalisation.

MHD Casson Fluid Flow over a Stretching Surface with Suction, Double Stratification, and Heat and Mass Transfer Effects

Abstract In this article, we investigated the flow of a magnetohydrodynamic Casson fluid across an extending surface with exponential permeability in a double-stratified medium. Thermal radiation, suction, heat sources, viscous dissipation, and chemical reactions drive the stream field. We converted the flow describing partial differential equations into terms of ordinary differential equations by applying appropriate transformations. Next, we utilised the bvp4c package in Matlab to obtain numerical solutions for these equations. We explored and graphically showed the implications of different non-dimensional governing parameters for temperature, concentration, and velocity profiles. After analysis, we provide a tabular presentation of the friction factor, Nusselt, and Sherwood numbers. The Casson fluid temperature shows a rising trend for the solutal stratification parameter and a decreasing trend for the thermal stratification parameter, while the Casson fluid velocity shows a declining trend towards both of these parameters. The Casson fluid concentration also behaves differently depending on the stratification parameter; for example, it increases for thermal stratification and decreases for solutal stratification. We notice that an increase in the Casson parameter's value suppresses the velocity field. However, as the Casson parameter increases, both the temperature and the concentration improve. Furthermore, comparisons with previously published findings also support the current results. \sethlcolor{yellow}\hl{The study of MHD Casson fluid flow that includes suction, dual stratification, and the effects of heat and mass transfer is very useful in many areas, such as polymer processing, metallurgical engineering, biomedical applications, environmental sciences, and advanced cooling technologies.

Impact of Thermal Energy on Water and Ethylene Glycol (50:50)-Based Rotating Hybrid Nanofluid Past A Riga Surface with Radiation, Homogeneous and Heterogeneous Reactions

Hybrid nanofluid is crucial in improving the efficiency of heat transmission in thermal engineering applications, particularly the cooling of electrical equipment, heat exchangers, fuel cells, printing machines, etc. This study sought to investigate the augmentation of heat and mass transmission by the use of a rotating hybrid nanofluid consisting of a mixture of gold and silver nanoparticles suspended in water and ethylene glycol (50:50) past a heated Riga surface with velocity slip and suction. The energy equation is constructed using nonlinear radiation and heat consumption. The impact of both homogeneous and heterogeneous processes on the hybrid nanofluid is also explored. The governing mathematical model begins with partial differential equations that are converted into ordinary differential equations using a suitable conversion technique. The results of numerical computations are recorded as graphs and tables using the bvp4c scheme in MATLAB. It is noticed that both directional velocities undergo significant negative changes as a result of enhanced values of the rotational parameter. The higher levels of the radiation parameter resulted in significant enhancements in the thermal profile. The falling behavior of the nanoparticle concentration profile is recorded against a greater quantity of both chemical reaction parameters. Based on our analysis, when the Biot number changes from 0.4 to 0.8, the most significant heat transmission gradient occurs.

Thermophoretic particle deposition effect on a squeezed flow of radiative Jeffrey fluid past a sensor surface with uniform heat source/sink and chemical reaction

Abstract This anticipated model investigates the time-dependent, and incompressible 2D magnetized Jeffrey liquid flowing on a sensor surface placed between two infinite parallel plates with the existence of a uniform heat source/sink. The lower plate remains fixed while the upper plate is subject to squeezing. For the heat and mass transmission processes, the consequences of radiative heat flux, chemical reaction, and thermophoretic particle deposition are applied and analyzed. The envisioned model is supported by prescribed heat and mass flux conditions. The uniqueness of the proposed model is the analysis of the unsteady squeezed flow of Jeffrey liquid over a sensor surface, accounting for radiative heat flux, thermophoretic particle deposition, and variable thermal conductivity. The model possesses applications in microfluidic sensors, biomedical devices, thermal management systems, and inkjet printing. The equations comprising the model are subject to similarity transformations. The bvp4c package is utilized to analyze the dynamic flow system. The connotation of arising parameters with the associated profiles is depicted through graphs and tables. It is examined that fluid velocity, temperature, and concentration profiles are dwindling functions of squeezed parameter. It is also witnessed that the concentration of liquid drops with an enhancement of thermophoretic and chemical reaction parameters. The validation of the truthfulness of the envisioned model is an added feature of this study.

Heat and mass flux dynamics of tangent hyperbolic nanofluid flow with unsteady rotatory stretching disk over Darcy-Forchheimer porous medium

Abstract The purpose of the research is to examine a tangent hyperbolic nanofluid flowing in three dimensions (3D) axisymmetrically on an unsteady rotatory stretching disk over a Darcy-Forchheimer porous medium. First order initial value problems (IVPs) are generated from the governing partial differential equations (PDEs) through the use of similarity transformation and linearization. The Runge-Kutta sixth order (RK6) is utilized to solve the IVP system using the shooting technique and the built-in Python program ‘fsolve model10’. Articles that have already been published are used to validate the implemented approach. Graphs are used to examine how various parameters affect velocity, temperature, and concentration. Additionally, the behavior of heat, mass flux, and skin friction in response to different parameters is investigated. The study’s findings showed that as the Forchheimer number and velocity slip parameter increased, the nanofluid’s radial and tangential velocities decreased as well. As temperature and concentration slip parameters increase, correspondingly, thicker and thinner boundary layer structures are seen. The drag force in the tangential and radial direction behaves in the same manner. Both the rates of heat and mass transfers are initiated for an increase Eckert and Prandtl numbers and demotivated for power-law index number. The dissipation effect with radiation and chemical reaction plays a major role in heat and mass fluxes, respectively. The study can be used in various computer storage, coatings, lubricants, and coolants.

Sensitivity study of heat transfer in a Jeffrey ferro-hybrid nanofluid bioconvective squeezing flow with inclined MHD and higher-order chemical reaction: entropy analysis

Abstract The present investigation concentrates on analyzing heat transfer and entropy formation in a time-reliant bioconvective flow of a blood-based Jeffrey hybrid nanofluid via a squeezing channel that is suctioned or injected at the lower plate. Cu nanoparticles and Fe3O4 ferro-nanoparticles are suspended in base-fluid blood. Adding ferro-nanoparticles to a flow process allows for better control of the external magnetic field and improved heat transmission. Noble integration of an aligned magnetic field, Joule's heating, thermal radiation, and higher-order chemical reactions is taken into account in the flow in a porous media. An appropriate choice of similarity variables leads to the non-dimensionalization of the governing equations, that are subsequently solved by the homotopy analysis method (HAM), yielding a semi-analytical solution. An innovative feature of this research is the optimization of heat transfer by the application of the response surface methodology (RSM) technique. Additionally, sensitivity analysis was carried out to identify the most influential parameter. The study's findings indicate that increased suction reduces both velocity and temperature distributions in both the nanofluid and hybrid nanofluid models. In terms of thermal performance, the Blood/Fe3O4 - Cu hybrid nanofluid surpasses the Blood/Fe3O4 nanofluid. The rate of thermal energy transfer is highly sensitive to variations in the Eckert number, while thermal radiation has a relatively lesser impact. Moreover, elevated levels of the magnetic parameter, Eckert number, and nanoparticle concentration lead to augmented entropy formation. This mathematical model is effective for analyzing drug transport mechanisms throughout the human body and presents extensive potential applications in the fields of biology and healthcare.

Effects of exponentially stretching sheet for MHD Williamson nanofluid with chemical reaction and thermal radiative

This paper explores the combined effects of heat radiation, viscous dissipation, and chemical reactions on the steady flow of Williamson nanofluid over an exponentially stretched sheet. The Governing non-linear Partial Differential Equations (PDE's), converted to couple nonlinear Ordinary ODE's by using similarity transformation, which are solved numerically using the Runge-Kutta-Fehlberg method along with the shooting technique. The study shows detailed analysis of the behaviour of Williamson nanofluid under the influence of thermal radiation and magnetic fields, having relevant industrial applications in cooling technologies and polymer processing. The results show that increasing the magnetic field parameter reduces the fluid velocity, while higher thermal radiation and Brownian motion parameters significantly enhance heat transfer rate withing the boundary region.

An in situ, prepulse insensitive and comparatively accurate intensity measurement of ultra-strong lasers based on stochastic radiation reactions

An in situ, prepulse insensitive and comparatively accurate intensity measurement of ultra-strong lasers based on stochastic radiation reactions

Impact of laser focusing and radiation reaction on particle spectra from nonlinear Breit-Wheeler pair production in the nonperturbative regime

Impact of laser focusing and radiation reaction on particle spectra from nonlinear Breit-Wheeler pair production in the nonperturbative regime

Initially reactive and concentrated generalized fluid wavy flow with the applications of disorder theory and magnetic field: A computational study

The wavy flow of generalized fluid namely, Cross fluid is mathematically formulated on a gravitationally affected vertical wavy surface with significant physical effects which is the main theme of this work. This particular dynamics of chemically reactive materials is further explored with an irreversible process. A significant heat transfer is measured through thermal resistance during the consideration of entropy optimization. Since entropy generation is associated with the mechanical systemenergy loss is more helpful in monitoring the entropy production in different engineering and industrial processes. Specifically, such irreversibility process appearance causing a noticeable low efficiency in the relevant practical sectors. For better performance in the minimization of friction on the wavy surface, flow is dissipated in terms of heat. However, the measure of loss in terms of work is introduced in the form of thermal radiation, viscous dissipation, magnetic field, and first-order chemical reaction. Additionally, the expected pressure drooping on the wavy surface is another goal of the entire study. The non-linear mathematical equations are determined by following the maximum viscosity approach. Relevant and important results are portrayed to show the various features of the newly developed work. The significant findings are approximated via one of the collocation methods while using MATLAB software. The Richardson number and buoyancy parameter enhanced the flow speed of the materials. The heat transfer rate is decreased by both Eckert number and wavy amplitude and the chemical reaction factor enhanced the mass transfer rate. The heat energy of the materials is escalated with the help of electromagnetic wave radiation and temperature ratio factor. Strengthening the chemical reaction factor declined the mass flow during the typical motion of the liquid. In the last, a comparison is provided to show the accuracy of the numerical approach.

Numerical Simulation of MHD Oldroyd-B Fluid with Thermal Radiation and Chemical Reactions Using Chebyshev Wavelets

The study has been carried out to analyze the Magnetohydrodynamic (MHD) boundary layer flow, heat and mass transfer of the two-dimensional viscoelastic Oldroyd-B fluid over a vertical stretching sheet in the presence of thermal radiation and chemical reaction with suction/injection in a steady state. The governing equations of the system are partial differential equations, which then give rise to a set of highly nonlinear coupled ordinary differential equations using similarity transformations. The nonlinearity in the differential equations is dealt with quasilinearization technique. The resultant equations are numerically solved using Chebyshev wavelet collocation method. The effects of magnetic field, radiation, chemical reaction and buoyancy parameters are investigated. The numerical values of local skin friction coefficient, local Nusselt number and local Sherwood number are also tabulated and analyzed. We observe that the increase in buoyancy parameters enhances the velocity profiles and larger values of magnetic field decrease the velocity profiles but increases the temperature and concentration profiles. Error analysis has been done to check the convergence of the numerical scheme.

Influence of scalar field in massive particle motion in JNW spacetime

In this paper, we investigated the motion of massive particles in the presence of scalar and gravitational fields, particularly focusing on the Janis-Newman-Winicour (JNW) naked singularity solution. It is shown that the innermost stable circular orbit radius strongly depends on scalar coupling parameter. Additionally, we explored the radiation reaction effects on particle dynamics, incorporating a reaction term into the motion equations. Numerical simulations indicated minimal impact on particle trajectories from radiation reaction. We also examined the oscillatory motion of particles around compact objects in the JNW spacetime, focusing on radial and vertical oscillations. Our analysis indicated that the scalar field’s coupling parameter and the spacetime deformation parameter n significantly alter the fundamental frequencies of these oscillations. Furthermore, we studied quasiperiodic oscillations (QPOs) in x-ray binaries, using the relativistic precession model to analyze upper- and lower-frequency relationships. Our results indicated that increasing parameters (n and gs) shifts the frequency ratio of 3∶2 QPOs closer to the naked singularity, with n decreasing and gs increasing both frequencies. Finally, we analyzed QPO data from four selected x-ray binary systems using Markov chain Monte Carlo analysis to constrain JNW parameters. Our findings provided insights into the mass, coupling, and deformation parameter for each system, enhancing our understanding of compact object dynamics in strong gravitational fields. Published by the American Physical Society 2024

Instantaneous and Retarded Interactions in Coherent Radiation.

In coherent radiation of an ensemble of electrons, the radiation field from electrons resonantly drives the other electrons inside to produce stimulated emission. The radiation reaction force on the electrons accounting for this stimulated radiation loss is classically described by the Liénard-Wiechert potential. Despite its being the foundation of beam physics for decades, we show that using the "acceleration field" in Liénard-Wiechert potential to describe radiative interactions leads to divergences due to its implicit dependence on instantaneous interactions. Here, we propose an alternative theory for electromagnetic radiation by decomposing the interactions into an instantaneous part and retarded part. It is shown that only the retarded part contributes to the irreversible radiation loss and the instantaneous part describes the space charge related effects. We further apply this theory to study the coherent synchrotron radiation energy loss, which hopefully will reshape our understanding of coherent radiation and collective interactions.

Quantum radiation reaction: Analytical approximations and obtaining the spectrum from moments

We derive analytical χ≪1 approximations for spin-dependent quantum radiation reaction for locally constant and locally monochromatic fields. We show how to factor out fast spin oscillations and obtain the degree of polarization in the plane orthogonal to the magnetic field from the Frobenius norm of the Mueller matrix. We show that spin effects lead to a transseries in χ, with powers χk, logarithms (lnχ)k, and oscillating terms, cos(…/χ) and sin(…/χ). In our approach we can obtain each moment, ⟨(kP)m⟩, of the light-front longitudinal momentum independently of the other moments and without considering the spectrum. We show how to obtain a low-energy expansion of the spectrum from the moments by treating m as a continuous, complex parameter and performing an inverse Mellin transform. We also show how to obtain the spectrum, without making a low-energy approximation, from a handful of moments using the principle of maximum entropy. Published by the American Physical Society 2024

The influence of a non-uniform heat source/sink and Joule heating on the convective motion of a micropolar fluid in a chemically radiative MHD medium across a stretched sheet

The objective of the present exploration is to examine impactions of radiation, a non-uniform intensity source, and a permeable medium on a temperamental MHD blended convective micropolar liquid over an extended sheet subject to Joule heating. To transform the formulated problem into ordinary differential equations, the applicable similarity transformation is implemented. By utilizing R-K-F 4th -5th order approach with shooting method with MATLAB, the numerical solution is obtained. For the relevant profiles, the dimensionless parameters are visually displayed and described. Skin friction, the Nusselt number, and the Sherwood number have all been calculated using the answer found for the velocity, temperature, and concentration. With the assistance of line graphs, the impact of different flow factors being introduced into the problem is addressed. This research is conducted on the implications of MHD, porous, thermal radiation, viscous dissipation, Joule heating, non-liner thermal radiation and chemical reaction. For large values of micropolar parameter, the temperature is reduced and velocity and angular momentum distributions are raised. With the thermal radiation parameter, the temperature distribution gets better and thermal boundary layer is improved while the large values of Eckert number and non-uniform heat source or sink parameters, thermal boundary layer is improved. The higher thermal conductivity is proportional to the thickness of the thermal boundary layer. The concentration profile degrades with higher Schmidt number and chemical reaction parameter values. The current examination pertains to the significant subject matter of cooling of systems, artificial heart identification, oil-pipelined frictions, flow-tracers.

Features of microorganism and two-phase nanofluid in a tangent hyperbolic Darcy-Forchhiemer flow induced by a stretching sheet with Lorentz forces

This work examines the two-dimensional tangent hyperbolic flow over a stretching sheet with a uniform magnetic field. The Buongiorno model is utilized to analyze and explain the spread of uneven coefficients in the presence of gyrotactic microorganisms. The concept of microorganisms and the resulting bioconvection enhance the stability of the nanoparticles. The impacts of thermal radiation, heat sources, convective heating, and chemical reactions are also evaluated. The suggested mathematical problem results in a nonlinear set of partial differential equations (PDEs), which are subsequently reduced to ordinary differential equations (ODEs) by applying the appropriate transformation. The resultant highly nonlinear ordinary differential equations (ODEs) are numerically solved using MATLAB's built-in package known as bvp4c. An in-depth investigation into the changes in the velocity field, the temperature profile, the concentration of nanoparticles profile, and the motile density profile is analyzed through graphs against various influencing parameters. Additionally, computations of engineering interest quantities such as skin friction, local Nusselt number, local Sherwood number, and molecular density are presented in both graphical and tabular formats for further examination. It has been explored that with greater values of the Weissenberg number, the fluid velocity upsurges when n<1, whereas the opposite behavior is noticed when n>1. It is also noted that an increment in the Peclet number decreases motile density for both dilatants n>1 and pseudoplastic n<1 fluids. The computed results are compared with existing literature in limiting cases and found good agreement.

Gravitational scattering and beyond from extreme mass ratio effective field theory

We explore a recently proposed effective field theory describing electromagnetically or gravitationally interacting massive particles in an expansion about their mass ratio, also known as the self-force (SF) expansion. By integrating out the deviation of the heavy particle about its inertial trajectory, we obtain an effective action whose only degrees of freedom are the lighter particle together with the photon or graviton, all propagating in a Coulomb or Schwarzschild background. The 0SF dynamics are described by the usual background field method, which at 1SF is supplemented by a “recoil operator” that encodes the wobble of the heavy particle, and similarly computable corrections appearing at 2SF and higher. Our formalism exploits the fact that the analytic expressions for classical backgrounds and particle trajectories encode dynamical information to all orders in the couplings, and from them we extract multiloop integrands for perturbative scattering. As a check, we study the two-loop classical scattering of scalar particles in electromagnetism and gravity, verifying known results. We then present new calculations for the two-loop classical scattering of dyons, and of particles interacting with an additional scalar or vector field coupling directly to the lighter particle but only gravitationally to the heavier particle.

The effect of carbon black on degradation of pipe grade black polyethylene in high concentration chlorine dioxide solutions

In this research, the impact of carbon black on the accelerated degradation of pipe grade polyethylene (PE100) exposed to high levels of chlorine dioxide (150 ppm) is examined. Tensile testing reveals a faster degradation rate in black samples compared to neat samples, indicating a detrimental effect of carbon black aggregates on the polymer's aging process. Rheological analysis shows changes in molecular weight and structure due to chemical degradation and chain scission and can be a reliable method for detecting slight changes in molecular structure. Isothermal crystallization shows a slowdown in crystallization kinetics at first, explained by gel-formation due to crosslinking which hinder the crystallization, and then an increase in the kinetics as apparently the chain scission gets dominant again. Neat samples exhibit a higher density of tie molecules, indirectly revealed by much more fibrils in crack wall observed in FESEM images, suggesting better resistance to chemical degradation while the black sample shows a much less fibrillar crack wake and becomes almost completely devoid of any fibrils at later stages of aging. The fibrils, which essentially offer a load-bearing role against the widening and growth of the crack play a key role in resistance to slow crack growth (SCG). Therefore, the higher SCG resistance is expected for neat grade compared to black samples. The study proposes a dual-layer pipe design with a UV-resistant black outer layer and an oxidation-resistant neat inner layer to prolong the lifespan of PE100 pipes by protecting against UV radiation and chemical reactions. This solution offers increased durability, lower maintenance costs, and environmental sustainability benefits.

Effective-one-body waveform model for noncircularized, planar, coalescing black hole binaries: The importance of radiation reaction

Effective-one-body waveform model for noncircularized, planar, coalescing black hole binaries: The importance of radiation reaction

Investigation of the Impact of a Chemical Reaction on the Magnetohydrodynamic Boundary Layer Flow of a Radiative Maxwell Fluid over a Stretching Sheet Containing Nanoparticles Employing the Variational Iteration Method

The heat and mass transmission properties of a 2-D electrically conducting incompressible Maxwell fluid past a stretched sheet were studied under thermal radiation, heat generation/absorption, and chemical reactions. This issue has a variety of real-world applications, most notably polymer extrusion and metal thinning. The transport equations account for both Brownian motion and thermophoresis during chemical reactions. Using similarity variables allows for non-dimensionalization of the stream's PDEs and associated boundary conditions. The resulting modified ODEs are solved with the variational iteration approach. The impact of embedded thermo-physical variables on velocity, temperature, and concentration was studied quantitatively. When compared to the RK-Fehlberg approach, the findings are very similar. Raising the chemical reaction parameter narrows the concentration distribution, whereas increasing the temperature increases thermal radiation's impact. As the amount of N_t increases, the thickness of the boundary layer develops, causing the surface temperature to rise, resulting in a temperature increase.