The development of a new high- delity methodology for predicting entry  ows with coupled radiation and ablation is described. The prediction methodology consists of an axisymmetric, nonequilibrium, Navier–Stokes  ow solver loosely coupled to a radiation prediction code and a material thermal response code. The methodology is used to simulate the 12.6-km/s Earth atmospheric entry of the Stardust sample return capsule using ablating and nonablating boundary conditions. These  ow simulations are used to size and design the Stardust forebody and afterbody heatshields and develop arcjet test conditions and models. The  ow simulations indicate that the afterbody heating and pressure pro les in time are signi cantly different than the forebody heating and pressure pro les. This result is explained in terms of the pertinent aerothermodynamicsof the  ow eld and the vehicle’s geometry.When applied to the afterbody thermal protection system, these results show that the traditional afterbody heatshield design approach is nonconservative for the Stardust sample return capsule shape and entry conditions.

Aerothermodynamics of the Stardust Sample Return Capsule

Collision integrals (transport cross sections ) of air species in the temperature range 50 ‐100,000 K have been calculated by using experimental and theoretical informations on potential energy curves and cross sections. The results for the different interactions (neutral‐neutral, neutral ‐parent ion, electron ‐neutral) have been compared with old and recent calculations obtaining, in general, a satisfactory agreement. Finally analytical forms for e tting and interpolating the present numerical results are reported.

Collision Integrals of High-Temperature Air Species

Thermodynamic and transport properties of high temperature equilibrium air plasmas have been calculated in a wide pressure (\(0.01\div100\) atm) and temperature range (\(50\div60\,000\) K). The results have been obtained by using a self-consistent approach for the thermodynamic properties and higher order approximation of the Chapman-Enskog method for the transport coefficients. Debye-Hukel corrections have been considered in the thermodynamic properties while collision integrals of charge-charge interactions have been obtained by using a screened Coulomb potential. Calculated values have been fitted by closed forms ready to be inserted in fluid dynamic codes.

Thermodynamic and transport properties in equilibrium air plasmas in a wide pressure and temperature range

Free underexpanded jets in a quiescent medium: A review

There has been a steady increase in the number of studies investigating educational robotics and its impact on academic and social skills of young learners. Educational robots are used both in and out of school environments to enhance K–12 students’ interest, engagement, and academic achievement in various fields of STEM education. Some prior studies show evidence for the general benefits of educational robotics as being effective in providing impactful learning experiences. However, there appears to be a need to determine the specific benefits which have been achieved through robotics implementation in K–12 formal and informal learning settings. In this study, we present a systematic review of the literature on K–12 educational robotics. Based on our review process with specific inclusion and exclusion criteria, and a repeatable method of systematic review, we found 147 studies published from the years 2000 to 2018. We classified these studies under five themes: (1) general effectiveness of educational robotics; (2) students’ learning and transfer skills; (3) creativity and motivation; (4) diversity and broadening participation; and (5) teachers’ professional development. The study outlines the research questions, presents the synthesis of literature, and discusses findings across themes. It also provides guidelines for educators, practitioners, and researchers in areas of educational robotics and STEM education, and presents dimensions of future research.

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A Systematic Review of Studies on Educational Robotics.

High-temperature transport properties (viscosity, thermal conductivity, binary and multicomponent mass diffusion, and thermal diffusion) of dissociating gases of the Earth and Martian atmospheres have been calculated within the framework of the Chapman -Enskog method. The exponential repulsion potentials of interactions between atoms (N, O, and C) and molecules (N2, O2, NO, C2, CN, CO, and CO2) were studied. The collision cross sections were calculated from numerous experimental molecular-beam scattering data. The bifurcation approximation to the binary diffusion coefficients and the Wilke-Saxena approximate techniques were effectively used to simplify numerical algorithms of heat transfer calculations.

Approximate calculation of transport coefficients of Earth and Mars atmospheric dissociating gases

Hypersonic viscous flows near simple-shape bodies (wedge, cone, disk, and plate) have been studied numerically under the conditions of wind-tunnel experiments. The Direct Simulation Monte-Carlo technique has been used to study the influence of similarity parameters (the Reynolds number, temperature factor, specific heat ratio, and viscosity-approximation parameter) on the flow structure near the bodies and on the aerodynamic coefficients in hypersonic streams of air, nitrogen, helium, and argon. The numerical results are in a good agreement with experimental data, which were obtained in a vacuum chamber at low and moderate Reynolds numbers from 0.1 to 200.

Comparative Similarity Analysis of Hypersonic Rarefied Gas Flows Near Simple-Shape Bodies

Nomenclature A = constant, Eq. (7) C = constant, Eq. (10) cf = friction coefficient cv = drag coefficient cv = lift coefficient ER = rotational energy G = transformed temperature function / = concentration of heavy component h — plate thickness / = Bessel function / = Bessel function K = hypersonic similarity parameter, M.^ sin a K2 = similarity parameter, Re*(p(llps)' Kff = relaxation parameter, p*u*r*/(pTR)* I = length of model M = Mach number M, = molecular weight of / species m — relaxation parameter, Eq. (10) n = exponent in the viscosity law JUL — T" (Pr.r 2) = average transition probability per one gas-kinetic collision for y* rotational level Pr = Prandtl number p = pressure q = dynamic pressure, {pyul_ R = asymptotic parameter, 0.75/te*,Rej = Reynolds number calculated by flow parameters in the nozzle exit cross section, p*u*rj/fj,j Re() = Reynolds number and the main similarity parameter, pyuJ,l[Ls Re* = Reynolds number calculated by flow parameters at the critical sphere, p*u*r*/iJi* r = distance from a nozzle exit along the ray rtl = location of the shock wave ("Mach disk") on the jet axis r,f = radius of spherical source Sc = Schmidt number s = exponent in the molecular interaction law T = temperature / = dimensionless temperature function, TIT^ tw = temperature factor, TJTS u = radial velocity component V = transformed velocity function, Eqs. (4) and (6) v' = tangential velocity component, Eq. (1) v = dimensionless velocity, M/M*,-, Eqs. (6) and (8) W = transformed velocity function, Eqs. (4) and (8) X = transformed coordinate, Eqs. (4) and (6) X = drag force x = inverse dimensionless radius, r^/r Y = lift force Z = transformed coordinate, Eq. (8) a = angle of attack /3 = thermal diffusion ratio y = ratio of specific heats 8 = dimensionless plate thickness, hll e = ratio of molecular weights, M1Ie/MAr 77 = argument for Bessel functions, Eq. (7) 0 = transformed temperature function, Eq. (8) 0 = angle between the body generatrix and the freestream flow A = expansion parameter, 2w(y 1), Eq. (4) fji = viscosity coefficient £ = deformable coordinate, Eq. (4) p = density r = relaxation time = transformed concentration function, Eq. (6) tp = angle between the ray from a nozzle exit and symmetry axis ^ = transformed concentration function, Eq. (8) a) = expansion parameter, l/[2y 1 2(y l)/i], Eq. (4)

Aerodynamic Applications of Underexpanded Hypersonic Viscous Jets

Enrollments in undergraduate computer science programs have declined steadily over the past few years. Overall, high school computer science curriculum is limited to either basic usage of Microsoft office tools or some advanced placement programming. Student expectations of undergraduate computer science courses for non-majors as well as the scope of computer science literacy in general are moving targets. All these problems have a negative impact on undergraduate recruitment and on promoting computing sciences courses and programs. In this paper we present our experience with a pre-college course in computing for high-school students offered at our College in the summer of 2004. We have learned promising lessons from running this program. These lessons can guide the curriculum design of computing courses for non-majors and motivate prospective students to pursue computer science programs.

Designing and running a pre-college computing course

The problem of redistribution of translational and rotational energy has been solved for diatomic gases within the framework of the Chapman ‐Enskog method and the Parker model in the general case of the arbitrary energy exchange ratio. The nonequilibrium gasdynamic equations, transport coefe cients, and relaxation time have been foundforrotational-translationalprocessesinadiatomicgas.Thecalculationsofrelaxationtime,viscosity,thermal conductivity, and diffusion coefe cients are carried out in thetemperature range from 200 to 10,000 K for nitrogen. The calculated parameters and coefe cients are compared with the values obtained by the Mason ‐Monchick approximatemethodaswellasdatafromexperimentsinultrasonic,shock-wave,and vacuumdevices.Thecorrelation of the theoretical and experimental data is satisfactory. The applicability of one- and two-temperature relaxation models is discussed. The numerical solutions of the obtained system of the Navier ‐Stokes equations are analyzed for the cases of spherical expanding nitrogen e ow and supersonic raree ed gas e ow near a sphere.

Vladimir V. Riabov

Papers

Approximate calculation of transport coefficients of Earth and Mars atmospheric dissociating gases

Comparative Similarity Analysis of Hypersonic Rarefied Gas Flows Near Simple-Shape Bodies

Aerodynamic Applications of Underexpanded Hypersonic Viscous Jets

Designing and running a pre-college computing course

Gas Dynamic Equations, Transport Coefficients, and Effects in Nonequilibrium Diatomic Gas Flows