Velocity Boundary Research Articles

Thermal performance and flow pattern of an immersion spray array cooling vapor chamber

An immersion spray array cooling vapor chamber (ISVC) is proposed for high-power electronic devices. Experimental and numerical studies on thermal performance and flow pattern have been conducted. It is shown that increasing the inlet temperature of the coolant facilitates the heat transfer performance and temperature uniformity of the ISVC within the safe working temperature range of electronic devices. The immersed spray impingement process includes a stage of velocity reduction from the nozzle exit to the target surface, a process of velocity boundary layer formation on the target surface, and a flow collision region formation process of adjacent sprays. As the inlet flow rate increases, the effect of the spray on the target surface is enhanced and the interaction between adjacent sprays is stronger. The perturbation effect of the spray on the fluid in the impingement cavity is positively influenced by the inlet flow rate. The spray array has a strong stirring effect on the water in the spray chamber in the XY, XZ and YZ planes. The heat transfer capacity of the ISVC is enhanced with a larger inlet flow rate due to the enhanced spray effect and larger spray coverage area. The temperature uniformity of the ISVC is improved with an increase of flow rate. The ISVC operating limit heating powers of 2.0 L/min, 4.0 L/min and 7.0 L/min flow rates are 531 W, 575 W and 600 W. Compared to the existing integrated heat sink combined vapor chamber and array jet impingement, the operating limit heating power of ISVC is increased by at least 68%.

A Multi-Scale Approach for Modelling Airborne Transport of Mucosalivary Fluid

COVID-19 pandemic promoted a lot of research activities in relation to mucosalivary fluid airborne transport. Indeed, infection mechanisms are the result of mucosalivary fluid droplets exchange and the knowledge in this area is still largely inadequate. One of the main challenges concerns the modelling of mucosalivary fluid complex nature. Specifically, this is a key element to predict small diameters dry nuclei formation which are highly relevant from the transmission risk point of view. For this reason, in this paper we present and discuss the development of a new multi-scale modelling technique which incorporates the Population Balance Equation into a standard particle-source-in-cell method. Thus, the effectiveness of the aforementioned technique in droplet nuclei generation modelling is showed and discussed. Also the impact of velocity boundary conditions at the mouth print is assessed as well as the effect of the correlations for mass transfer showing that their neglect causes an underestimation in distance reached by the droplets.

Ramping Wall Boundary Analysis of Buoyant-Driven Convection Magnetohydrodynamics (MHD) Flow of B–H2O and Al2O3–H2O Nanofluid Past Vertical Edge in a Porous Zone

An analysis is explored to study ramping wall velocity, temperature and concentration as well as isothermal case of a nanofluid flow, suspended boron and aluminium oxide nanoparticles in the seawater at 20°celcius influenced by magnetic and gravitational forces in a semi-infinite flow region using integral transform method. Thermal radiation and heat injection/suction are also investigated. Rosseland’s approximation is used for radiative heat flow in the energy equation, whereas Bousinessq’s approach is used in the momentum equation. Fluid temperature, species concentration, and transport are solved using Heaviside, exponential and complementary error functions; friction drag, heat and mass transfer rates are solved using Gaussian error functions. Temperature, transport and species concentration are graphically exhibited while the numerical calculations have been carried out for friction drag, rate of heat transmission and Sherwood number are performed for both the ramped wall and isothermal cases, and the effects of emerging parameters are tabulated and discussed. Higher radiation parameters lead to an increase in fluid temperature. The velocity boundary layer is lowered by the magnetic field and porous media parameters. The Nusselt number drops as Prandtl number, radiation parameter and volume fraction grows for both ramping and isothermal situations, whereas increases when time and heat source parameter increases.

An implicit Keller box approach for solution of MHD three-dimensional flow through a porous medium

The present study investigates the Soret and Dufour effect on free-convection flow of a viscous incompressible fluid through a porous medium bounded by an infinite vertical porous plate with chemical reaction and viscous dissipation is investigated with aid of Implicit Keller box and regular perturbation methods. The flow is assumed in the presence of transverse magnetic field. Characteristics of Velocity, Temperature and Concentration are obtained and graphical interpretation is made. The observation of these results reflects that velocity and thermal boundary layer thickness decrease with the increase of radiation parameter. Graphical interpretations establish a good agreement in a realistic sense.

An explicit and non-iterative moving-least-squares immersed-boundary method with low boundary velocity error

In this work, based on the moving-least-squares immersed boundary method, we proposed a new technique to improve the calculation of the volume force representing the body boundary. For boundary with simple geometry, we theoretically analyze the error between the desired volume force at boundary and the actual force given by the original method. The ratio between the two forces is very close to a constant and exhibits a very narrow distribution. A spatially uniform coefficient is then introduced to correct the force and can be fixed by the least-square method over all boundary markers. Such method is explicit and non-iterative, and is easy to implement into the existing scheme. Several test cases have been simulated with stationary and moving boundaries. Our new method can reduce the residual boundary velocity to the level comparable to that given by the iterative method, but requires much less computing time. Preliminary test suggests that the current method is also effective for nonuniform Eulerian grid. Moreover, the new method can be readily combined with the iterative method and further reduces the residual boundary velocity.

The influence of boundary conditions on simulation of pressure wave reflection in a pipe

Previous studies have demonstrated that the flow characteristics of pressure waves in hydraulic experiments show two types of reflected waves: those with the same type pressure vibration trend and those with the opposite vibration trend, with the pressure amplitude equal to that of the original wave. Reflection characteristics in a simulation must be consistent with those found experimentally. To determine reasonable boundary conditions (BCs), the focus of this work was the simulation of pressure wave reflection under five combinations of BCs using computational fluid dynamics. Three three-dimensional simulation models were developed based on the k–ε turbulence model. Reflection characteristics were obtained under the different BCs. The results showed that the pressure boundary in the pipe simulated the reflected waves correctly. The reservoir was found to be more accurate than the pressure boundary, which reflected the slight fluctuation in the reflected wave. Both the wall boundary and the velocity boundary could be used to simulate valve operation. However, if intercepting part of the pipeline, the reflected wave showed phase advance and pressure amplitude attenuation compared with that at the same position in the original pipeline. This study is helpful for setting reasonable BCs in pressure wave simulations.

Numerical Solutions on Reiner–Philippoff (RP) Fluid Model with Velocity and Thermal Slip Boundary Condition

Non-Newtonian fluid model was created against the Newton’s Law of viscosity where the viscosity is no more constant and dependent on the shear rate. The existing such fluid can be found in many industrial claims especially in food manufacturing, lubrication, biomedical flows and oil and gas. Besides, the used of non-Newtonian fluid occurs in mining industry where the slurries and muds are often handled. There are many models on non-Newtonian fluid available in literature where some of them capture the specific properties. The Reiner–Philippoff (RP) fluid model is considered in this endeavour due to the capabilities of the model which can be acted in three different family of fluid which are viscous, shear thickening and the shear-thinning. Mathematical model is constructed using continuity, momentum and energy equations where in form of partial differential equations (PDEs). The complexity of the proposed model is abridged by deduced the equations into ordinary differential equations (ODEs) by adopting similarity variables before the computation is done by bvp4c function drive in MATLAB software. To ratify the validity of the proposed model as well as numerical outputs, the comparative study is performed and it found to be in very strong agreement under limiting case where the present model is condensed to be identical with the reported model previously. The consequences of pertinent parameters on fluid’s characteristics are analyzed in details through the plotted graphic visuals and tabular form.

Dynamic behavior of a magnetorheological fluid radial-flow-based energy absorber considering apparent slip boundary condition

Accurate theoretical models play a key role in the development of magnetorheological energy absorbers (MREAs). Traditionally, the apparent slip caused by non-uniformity interface (i.e., the separation of carrier fluid and magnetic particles at the wall) of the working medium is often ignored for simplifying theoretical models. However, the apparent slip influence the cross-sectional flow and decreased the theoretical accuracy of the damping force for MREA applied in the impact absorption area. In this study, a dynamic model with apparent slip boundary condition for radial-flow-based MREA was proposed. The effect of apparent slip layer thickness on the dynamic behavior of an MREA was qualitatively and quantitatively compared in terms of the following three aspects: (1) with the Power-Law constitutive model, theoretical models of the dynamic characteristics of the magnetorheological fluid (MRF) squeeze and MREA are presented based on the apparent slip boundary condition with the MRF behavior of the Navier–Stokes equation; (2) the accuracy of the theoretical model to predict MREA peak force and boundary velocity with different slip-layer thicknesses; and (3) global agreement of the dynamic force and range curves between the modeling and experimental results. The results show that the absolute values of the relative errors in the two models with a 2- and 0-µm thick slip layer were less than 3.73 and 7.41%, respectively, and that a 2-µm thickness can help predict the actual dynamic characteristic more efficiently under accidental collision loading conditions.

Experimental Evidence for the Existence of the Ultimate Regime in Rapidly Rotating Turbulent Thermal Convection.

What is the final state of turbulence when the driving parameter approaches infinity? For the traditional Rayleigh-Bénard convection, a possible ultimate scaling dependence of the heat transport (quantified by the Nusselt number Nu) on the Rayleigh number (Ra), which can be extrapolated to arbitrarily high Ra, is predicted by theories. The existence of the ultimate scaling has been intensively debated in the past decades. In this Letter, we adopt a novel supergravitational thermal convection experimental setup to study the possible transition to the ultimate regime. This system is characterized by the combined effects of radial-dependent centrifugal force, the Earth's gravity, and the Coriolis force. With an effective gravity up to 100 times the Earth's gravity, both Ra and shear Reynolds number can be boosted due to the increase of the buoyancy driving and the additional Coriolis forces. With over a decade of Ra range, we demonstrate the existence of ultimate regime with four direct evidences: the ultimate scaling dependence of Nu versus Ra; the appearance of the turbulent velocity boundary layer profile; the enhanced strength of the shear Reynolds number; and the new statistical properties of local temperature fluctuations. The present findings will greatly improve the understanding of the flow dynamics in geophysical and astrophysical flows.

Entropy Analysis of EMHD Hybrid Nanofluid Stagnation Point Flow over a Porous Stretching Sheet with Melting Heat Transfer in the Presence of Thermal Radiation

In this study, the entropy formation of an electromagnetohydrodynamic hybrid nanofluid at a stagnation point flow towards a stretched surface in the presence of melting heat transfer, second-order slip, porous medium, viscous dissipation and thermal radiation are investigated. Hybrid nanoparticles alumina (Al2O3) and copper (Cu) are considered, with the base fluid water (H2O). Similarity transformations are used to address the governing partial differential equations (PDEs) that lead to the corresponding ordinary differential equations. The resulting ODEs are solved by employing bvp4c solver numerically in the MATLAB package. The effects of temperature, transport, production of entropy and Bejan number Be are graphically exhibited. Higher radiation parameters R and an electric field E lead to an increase in fluid temperature. The velocity boundary layer is lowered by the magnetic field and porous media parameters. The opposite behaviour is observed in the electric field E. As a result, hybrid nanofluid has numerous uses in engineering cosmetics, automotive industry, home industry, for cancer treatment, food packaging, pharmaceuticals, fabrics, paper plastics, paints, ceramics, food colorants, electronics, heat exchangers, water purification, lubricants and soaps as well.

Effects of kinematic and magnetic boundary conditions on the dynamics of convection-driven plane layer dynamos

Rapidly rotating convection-driven dynamos are investigated under different kinematic and magnetic boundary conditions using direct numerical simulations. At a fixed rotation rate, represented by the Ekman number$Ek=5\times 10^{-7}$, the thermal forcing is varied from$2$to$20$times its value at the onset of convection ($\mathcal {R}=Ra/Ra_c=2\unicode{x2013}20$, where$Ra$is the Rayleigh number), keeping the fluid properties constant ($Pr=Pr_m=1$, where$Pr$and$Pr_m$are the thermal and magnetic Prandtl numbers). The statistical behaviour of the dynamos, including the force balance, energetics, and heat transport, depends on the boundary conditions that dictate both the boundary layer and the interior dynamics. At a fixed thermal forcing ($\mathcal {R}=3$), the structure and strength of the magnetic field produced by the dynamos, especially near the walls, depend on both velocity and magnetic boundary conditions. Though the leading-order force balance in the bulk remains geostrophic, the Lorentz force becomes comparable to the Coriolis force inside the thermal boundary layer with no-slip, perfectly conducting conditions. In this case, a term signifying the work done by the Lorentz force in the turbulent kinetic energy (TKE) equation is found to have some components that extract energy from the velocity field to produce the magnetic field, while some other components extract energy from the magnetic field to produce TKE. However, with no-slip, pseudo-vacuum conditions, all the components of the work done by the Lorentz force perform unidirectional energy transfer to produce magnetic energy from the kinetic energy of the fluid to sustain dynamo action. We find heat transfer enhancement in the rotating dynamo convection, as compared with non-magnetic rotating convection, with the peak enhancement lying in the range$\mathcal {R}=3\unicode{x2013}4$. For free-slip conditions, in the absence of an Ekman layer, the dynamo action may alter the heat transport significantly by suppressing the formation of large-scale vortices. However, the highest heat transfer enhancement is found at$\mathcal {R}=3$with no-slip, perfectly conducting walls, which can be attributed to a local magnetorelaxation of the rotational constraint due to enhanced Lorentz force inside the thermal boundary layer.

Analysis of Reciprocal Thermal Conductivity on Free Convection Flow along a Wavy Vertical Surface

The effects of thermal conductivity which depend on temperature are conversely proportional with the linear function of temperature on free convective flow where the fluid is viscous and incompressible along a heated uniform and the vertical wavy surface has been examined in this study. The boundary layer equations with the associated boundary conditions that govern the flow are converted into a nondimensional form by using an appropriate transformation. In the domain of a vertical plate that is flat, the resulting method of nonlinear PDEs is mapped and then worked out numerically by applying the implicit central finite difference technique with Newton’s quasilinearization method, and the block Thomas algorithm is well known as the Keller-box method. The outputs are obtained in the terms of the heat transferring rate, the frictional coefficient of skin, the isotherms, and streamlines. The outcomes showed that the local heat transferring rate, the local skin friction coefficient, the temperature, and the velocity all are decreasing, and both the thermal layer of boundary and velocity become narrower with the rising values of reciprocal variation of temperature-dependent thermal conductivity. On the other hand, the friction coefficient of skin, the velocity, and the temperature decrease where the friction coefficient of skin and velocity decrease by 43% and 64%, respectively, but the heat transfer rate increases by 61% approximately, and both the boundary layer thermal and velocity become thinner when the Prandtl number increases.

Two Component Benard-Marangoni Convection in a Composite System Subjected to Variable Heat Source

Double diffusive convection is the phenomena that describes the convection driven by two differ-ent densities which have different rates of diffusion. A comparison of two temperature boundaries when i) both the surfaces are set at adiabatic temperature, and ii)upper free surface is adiabatic and lower rigid surface is isothermal cases, on surface tension driven double diffusive convection in a horizontal composite layer is studied analytically using exact method. For both cases i) and ii), the thermal Marangoni number (Tmn) is determined, which is the eigen value, for upper free and lower rigid velocity boundary conditions. The results indicate that the given system is a fluid dominant composite system and adiabatic-isothermal thermal boundary is more stable compare to adiabatic-adiabatic boundary condition.

Numerical visualisation on the impact of setting convective velocity of outflow boundary on a parallel grid-generated flow

This study approaches a widely used convective outflow condition for analysing turbulent flow fields with a freestream to clarify effects of the convection velocity setting. Previous studies have often used a local velocity at the outflow boundary. This study uses the setting of the outflow condition described in the previous Orlanski’s study. In this study, a two-dimensional flow induced by a parallel grid is analysed. The governing equations are spatially discretised by a second-order central difference method and integrated in the time domain using the fourth-order Runge-Kutta method. We can observe wavy profiles near the outflow boundary that vary in the streamwise direction. These wavy profiles are more evident when the local velocity is used as the convective velocity. The effect of the setting outflow velocity on the turbulence structure characterised using the second invariant of the velocity gradient tensor is also investigated.

Heat transportation performance and entropy generation analysis of Iron (II, III) oxide microparticles on Taylor Couette flow over a slit wall

Despite the significance of Taylor Couette flow over a slit wall in industries, little is known about the impact of Iron (II, III) oxide (Fe3O4) microparticle on the dynamics and heat transfer properties of Taylor-Couette flow. This study aims to investigate the effect of solid particles on heat transfer performance of Taylor-Couette flow over a slit wall. The trajectory of particles in the flow field is described utilizing Eulerian-Lagrangian method in this report. The Fe3O4-water suspension with particle size dp = 1μm, 5μm and particle volume fraction φ = 0.5 % , 1.0 % , 1.5% are considered. Results reveal that the heat transfer performance of Taylor vortex is remarkable enhanced by adding the solid particles inside the annular gap compared to pure water. Solid particles in the annular gap show the movement of migration from inner to outer cylinders due to the interaction with fluid, which causes more disordered flow field around the inner cylinder. The addition of particles could significantly thin the velocity and temperature boundary layers. Frictional and thermal entropy generation display a reverse tendency with increasing particle volume fraction and size. Thermal entropy generation appears obviously higher than frictional entropy generation. Suspension with φ = 1.5% and dp = 1μm makes optimal performance of Taylor vortex because of the minimum entropy generation and boundary layers.

Piloted ignition of vertical polymethyl methacrylate (PMMA) exposed to power-law increasing radiation

• Temperature-dependent thermodynamics is determined by inverse modelling. • Top ignitor shortens ignition time compared to center ignitor. • Volatile concentration at top ignitor is 2.5 – 3.5 times of that at center ignitor. • Thermal boundary layer remains invariant at ignition time with changing heat flux. • Ignition criteria of center ignitor are larger than those of top ignitor. Piloted ignition of vertically mounted solid induced by time-dependent radiation, which is frequently encountered in practical scenarios, is barely examined in existing studies. This contribution experimentally addresses piloted ignition of vertically mounted polymethyl methacrylate (PMMA) heated by five power-law increasing heat fluxes. Susceptibility feature of ignition to ignitor position was examined by selecting two ignitor locations (top and center). A condensed phase analytical model and a solid-gas numerical solver were established to analyze experimental results. Temperature-dependent thermal conductivity and specific heat of PMMA were determined by inversely modelling measured surface temperature and mass loss rate at an intermediate radiation level. Meanwhile, simulated evolutions of surface temperature, mass loss rate, pyrolyzate concentration, streamlines as well as thermal, species and velocity boundary layers were demonstrated and discussed. The results show that top ignitor shortens ignition time due to buoyancy-induced accumulation effect of volatiles, which consequently leads to lower critical temperature and critical mass loss rate. The numerical model successfully predicts measured experimental results, but the analytical model overestimates surface temperatures and underpredicts ignition times owing to the neglect of pyrolysis. At ignition time, the thermal boundary layer remains approximately unchanged with varying heat fluxes. Measured critical temperatures for center and top ignitors are 651 K and 641 K, while the corresponding critical mass loss rates are 10 g m −2 s −1 and 4.5 g m −2 s −1 , respectively.

Studies on flow field, and instabilities in a large diameter opposed jet burner

This work reports studies on flow fields, and instabilities exhibited by opposed jets at equal momenta, for Reynolds numbers (Re) ranging from 178 to 5000 using a large diameter counterflow jet setup. Flow instability investigations were conducted over a range of aspect ratios (α) too. This study identifies the regions of bi-stability and those of oscillatory stagnation plane offsets identified by Re. Experiments on flow field were carried out using particle image velocimetry technique, and the paper presents the axial and radial velocity profiles at various locations as well as their gradients. A decreasing trend in stagnation plane displacements with the Reynolds number was observed. The experiments in comparison with the past literature suggest a possible dependence of the stagnation plane displacements on a nozzle-exit diameter. The trends in maximum stagnation plane displacements (δmax), as well as the critical Reynolds numbers (Recr) with aspect ratios (α), are analyzed and compared. The flow field studies reveal the need for two dimensional axisymmetric simulations with realistic velocity boundary conditions to predict opposed jet flow phenomena accurately. Reacting flow instability studies were also carried out for equal momenta using methane-air and ethylene–air flames at various aspect ratios. The results show an enhanced bistability for ethylene–air flames over methane–air flames.

Influence of chemical kinetic exponent on transient mixed convective hydromagnetic flow in vertical channel with convective boundary condition

A flow that is subject to the influence of both thermal buoyancy and pressure gradient is called mixed convection. This kind of flow can be found in a wide variety of scientific and infrastructural functionalities, such as sunlight transceivers that are open to the airflow, digital devices that are kept cool by fans, nuclear reactors that are cooled during emergency shutdowns, and heat exchangers that are placed in low-velocity environments. This paper present MHD coupled convection flow of chemical reaction of an exothermic and chemical kinetic fluid with Newtonian heating in a vertical channel. chemical reaction (λ), magnetohydrodynamics ( Ha ), Navier slip (Γ), and Newtonian heating ( Br ) are all taken into consideration, in addition to the chemical kinetic exponent ( m ). Homotopy perturbation techniques and implicit finite difference scheme are used to find the steady-state solution and transient state solution for the set of dimensionless coupled governing equations. The rate of heat transfer and sheer stress were derived by differentiating the analytical solution obtained. Various pertinent parameters controlling the flow such as chemical reaction parameter (λ), MHD ( Ha ), Newtonian heating parameter ( Br ), chemical kinetic exponent ( m ) and Navier slip parameter (Γ) are illustrated graphically. Velocity and temperature fields are also demonstrated. The studies showed that a little rise in the Hartman number induces the Lorentz force, which streamlines the velocity boundary layer, decelerating the flow. A minor increase in the mixed convection parameter, on the other hand, resulted in significantly enhanced flow profiles, resulting in a greater flow rate during biomolecular kinds of chemical processes. Also during course of computation, the energy and velocity profiles improve with increase in (λ), ( Br ), ( m ),(γ) and ( Gre ). However, a graphical comparison of the transient solution and the steady state solution was also displayed, with an outstanding agreement.

Boundary Stability Criterion for a Nonlinear Axially Moving Beam

This article deals with, in the framework of absolute stability, boundary stabilization for a nonlinear axially moving beam under boundary velocity feedback controls. The nonlinear boundary control that satisfies a slope-sector condition covering many types of nonlinear control schemes is a negative feedback of the transverse velocity at the right eyelet of the moving beam. Under the nonlinear control scheme, the well-posedness of the nonlinear partial differential equation, which depends continuously on the initial value is investigated by means of the Faedo–Galerkin approximation and priori estimates. By exploiting the integral-type multiplier method, the exponential stability of the closed-loop system is established, where a novel energy like function is constructed. The numerical simulation examples using the finite element method are presented to illustrate the effectiveness of the established criterion of the controller.

A coupled model for phase mixing, grain damage and shear localization in the lithosphere: comparison to lab experiments

SUMMARYThe occurrence of plate tectonics on Earth is rooted in the physics of lithospheric ductile weakening and shear-localization. The pervasiveness of mylonites at lithospheric shear zones is a key piece of evidence that localization correlates with reduction in mineral grain size. Most lithospheric mylonites are polymineralic and the interaction between mineral phases, such as olivine and pyroxene, especially through Zener pinning, impedes normal grain growth while possibly enhancing grain damage, both of which facilitate grain size reduction and weakening, as evident in lab experiments and field observations. The efficacy of pinning, however, relies on the mineral phases being mixed and dispersed at the grain scale, where well-mixed states lead to greater mylonitization. To model grain mixing between different phases at the continuum scale, we previously developed a theory treating grain-scale processes as diffusion between phases, but driven by imposed compressive stresses acting on the boundary between phases. Here we present a new model for shearing rock that combines our theory for diffusive grain mixing, 2-D non-Newtonian flow and two-phase grain damage. The model geometry is designed specifically for comparison to torsional shear-deformation experiments. Deformation is either forced by constant velocity or constant stress boundary conditions. As the layer is deformed, mixing zones between different mineralogical units undergo enhanced grain size reduction and weakening, especially at high strains. For constant velocity boundary experiments, stress drops towards an initial piezometric plateau by a strain of around 4; this is also typical of monophase experiments for which this initial plateau is the final steady state stress. However, polyphase experiments can undergo a second large stress drop at strains of 10–20, and which is associated with enhanced phase mixing and resultant grain size reduction and weakening. Model calculations for polyphase media with grain mixing and damage capture the experimental behaviour when damage to the interface between phases is moderately slower or less efficient than damage to the grain boundaries. Other factors such as distribution and bulk fraction of the secondary phase, as well as grain-mixing diffusivity also influence the timing of the second stress drop. For constant stress boundary conditions, the strain rate increases during weakening and localization. For a monophase medium, there is theoretically one increase in strain rate to a piezometric steady state. But for the polyphase model, the strain rate undergoes a second abrupt increase, the timing for which is again controlled by interface damage and grain mixing. The evolution of heterogeneity through mixing and deformation, and that of grain size distributions also compare well to experimental observations. In total, the comparison of theory to deformation experiments provides a framework for guiding future experiments, scaling microstructural physics to geodynamic applications and demonstrates the importance of grain mixing and damage for the formation of plate tectonic boundaries.