Fluid Sciences and Materials Science in Space

I. The Environment of Earth-Orbiting Systems.- A. Introduction.- B. Low Gravity Simulation.- B.1 Simulation of Weightlessness.- B.2 Orbital Flight.- B.2.1 Spacecraft in Circular Orbit.- B.2.2 Actual Gravitational Environment Aboard a Spacecraft.- B.2.3 A Case Study: The Microgravity Environment of the Orbiter/Spacelab System.- B.3 Other Free-Fall Methods.- B.3.1 Sounding Rockets.- B.3.2 Research Aircraft.- B.3.3 Drop Tubes and Drop Towers.- C. Atmospheric Conditions, Radiation and High Energy Particles.- C.1 Introduction.- C.2 Radiation Environment.- C.3 Atmospheric Environment.- C.4 High Energy Particles.- D. Conclusions.- E. References.- I. Fluid Sciences.- Fluid Physics.- II. Fluid Statics and Capillarity.- A. Introduction.- B. Basic Physics.- B.1 Influence of Gravity.- B.2 Macroscopic and Microscopic Views of the Interface.- B.3 Thermodynamics of the Gibbs Model.- B.4 Capillary Equilibrium.- B.5 Capillary Stability.- B.6 Rotational Stability.- B.7 Critical Wetting.- B.8 Charged Interfaces.- C. Results of Previous Microgravity Experiments.- C.1 Static Equilibrium and Stability.- C.2 Rotation and Oscillation.- C.3 Critical Wetting.- C.4 Charged Interfaces.- D. Future Prospects.- D.1 Present Interests.- D.2 Topics to Be Addressed in the Future.- D.3 General Remarks.- F. References.- III. Fluid Dynamics.- A. Introduction.- B. Inertial, Internal and External Forces.- C. General Momentum Equation.- C.1 Perfect Fluids.- C.2 The Momentum Equation.- C.3 Navier-Stokes Equation.- C.4 Physical Meanings of Terms for Different Flows.- C.5 Influence of Gravity.- C.5.1 Hydrostatic Distribution of Pressure.- C.5.2 Mechanical Stability.- C.5.3 Stream Functions.- C.5.4 The Shape of a Surface.- C.5.5 Gravitational Waves in Perfect Fluids.- C.5.6 Particular Cases for Perfect Fluids.- C.5.7 Influence of Gravity on Viscous Fluids.- D. Similarity Laws.- E. Surface Forces and Hydrodynamical Instabilities.- E.1 Heat Transfer.- E.2 Laplace Law.- E.3 Influence of Gravity on the Shape of a Liquid Film.- E.4 Capillary Waves.- E.5 Capillary Gravitational Waves.- E.6 Rayleigh-Bénard Instability.- E.7 Two-Component Rayleigh-Bénard Convection.- E.8 Steady Cellular Marangoni-Bénard Convection (Thermocapillary Flow).- E.9 Oscillatory Marangoni-Bénard Convection with Interfacial Deformation.- E.10 Rayleigh-Taylor Instability for Pure Liquids.- E.10.1 Inviscid Fluids.- E.10.2 Immiscible, Inviscid, Uniform Fluids.- E.10.3 Exponentially Varying Density in an Inviscid Fluid.- E.10.4 Two Uniform Viscous Fluids Separated by a Horizontal Boundary.- E.10.5 Uniform Rotation.- E.11 The Kelvin-Helmholtz Instability.- E.11.1 Two Uniform Inviscible Fluids in Relative Motions.- E.11.2 Transition Layer with Continuous Variation of Velocity.- E.11.3 Continuous Density and Velocity in an Incompressible Fluid.- E.12 Mechano-Diffusional Instability.- E.12.1 Basic Equations.- E.12.2 Stability Criteria for Plane Interfaces.- E.12.3 Stability Criteria for Spherical Interfaces.- E.13 Mechano-Chemical Reactions.- E.13.1 Isothermal Surface Reaction.- E.13.2 Reaction in an Isothermal Layer.- F. Some Results of Fluid Dynamics Experiments Under Microgravity Conditions.- G. Conclusions.- H. Annex: Some Dimensionless Groups and Their Relevance of Fluid Dynamics in Space.- I. References.- Physical Chemistry.- IV. Physical Chemistry — Overview and Selected Experiments.- A. Introduction.- B. Elements of the Present Microgravity Research Programme.- B.1 Thermodynamics and Transport Properties.- B.2 Phase Transitions and Near-Critical Point Phenomena.- B.3 Wetting and Adsorption Phenomena, Nucleation and Ageing.- B.4 Combustion and Chemical Reactions.- C. Additional Perspectives.- C.1 Relaxation Phenomena.- C.2 Applied Electrochemistry and Process Engineering.- D. Conclusions and Outlook.- E. References.- V. Mass Transport by Diffusion.- A. Introduction.- B. Relevance of Microgravity.- B.1 Advantages.- B.1.1 Heterodiffusion.- B.1.2 Self-diffusion.- B.1.3 Thermotransport.- B.1.4 Electrotransport.- B.2 Problems.- B.2.1 Macro- and Microconvection.- B.2.2 Marangoni Convection.- B.2.3 Free Volumes.- B.2.4 Influence of Segregation.- B.2.5 Wall Effects.- B.2.6 Time-Temperature Boundary Conditions.- B.2.7 Geometrical Boundary Conditions.- C. Results of Experiments.- C. 1 Experimental Techniques.- C.2 Analytical Methods.- C.3 Main Results.- C.4 Diffusion Data.- D. Analysis of Prospects.- E. References.- VI. Wetting and Adsorption Phenomena.- A. Introduction.- B. Gravity Effects on Interfaces.- B.l Liquid-Vapour Interface.- B.2 Wetting and Contact Angles.- B.3 Wetting Transition.- B.4 Critical Adsorption.- C. Theoretical Background.- C.1 Landau Theory.- C.1.1 Interface Between Two Coexisting Phases.- C.1.2 Wetting and Wetting Transitions.- C.1.3 Scaling.- C.1.4 Critical End Point Behaviour.- C.2 Other Theories.- C.2.1 Mean Field Theory for Systems with Long Ranged Interactions.- C.2.2 Beyond Mean Field Theory.- D. Experimental Status.- D.1 Thickness of Wetting Layers.- D.2 Critical Adsorption.- E. Outlook.- F. References.- VII. Phase Transitions and Near-Critical Phenomena.- A. Introduction.- B. Fundamentals.- B.1 Thermodynamics of Phase Transitions.- B.2 Classical Description; Mean Field Theory.- B.3 Scaling Laws.- B.4 Fluctuations and Correlations.- B.5 Renormalization Group Approach.- B.6 Transport Properties.- B.7 Approach to Equilibrium.- B.8 Phase Separation Process, Nucleation and Spinodal Decomposition.- B.9 Adsorption and Wetting.- B.10 The ?-Point of Helium.- B.11 Electrolyte Solutions.- C. Why Microgravity?.- C.1 Influence of Compressibility.- C.2 Influence of Isochoric Expansion Coefficient.- C.3 The Phase Separation Process.- C.4 Wetting Layers.- C.5 Interface Stability and Capillary Waves.- D. Status of Experimental Investigations.- D.1 Specific Heat in a Liquid-Vapour Transition.- D.2 Phase Separation Process.- D.2.1 Phase Separation and Phase Mixing of Near-Critical SF6.- D.2.2 Density Distribution Near the Critical Point in a Microgravity Environment.- D.2.3 Phase Separation of a Critical Mixture of Isobutyric Acid and Water.- D.2.4 Phase Separation of Critical and Near-Critical Mixtures of Cyclohexane-methanol and of Their Deuterated Derivatives.- D.2.5 Phase Separation After Stirring in Aqueous Polymer Mixtures.- D.3 Aqueous Salt Solutions.- E. Prospectives.- E.1 Equilibrium Thermodynamic Properties.- E.2 Approach to Equilibrium (Pure Fluids).- E.3 Transport Properties.- E.4 Phase Separation Processes.- E.5 Interfacial Phenomena.- E.6 Electrolyte Solutions.- F. References.- VIII. Chemical Pattern Formation.- A. Description and Definition of the Phenomenon.- B. Theoretical Concepts.- B.1 Chemical Instabilities.- B.2 Reaction-Diffusion Systems.- B.3 Additional Hydrodynamical Fluxes and Gravity.- C. Experimental Evidence.- C.1 Chemical Waves.- C.2 Precipitation Patterns.- C.3 Influence of Convection.- C.3.1 Hydrodynamic Flow.- C.3.2 Interfacial Instabilities.- D. Applications.- D.1 Inanimate Nature.- D.2 Biology.- D.2.1 Polarization and Morphogenesis.- D.2.2 Control of Membrane Functions.- D.2.3 Rhythms.- D.2.4 Motions.- D.3 Crosscorrelations.- E. Avenues for Microgravity Experimentation.- F. References.- IX. Combustion.- A. Introduction.- B. Fundamental Considerations.- B.1 Combustion Processes.- B.2 Time Scales in Combusting Flows.- B.3 Characteristics of Combusting Flow Fields.- C. Experimental Limitations and Solutions.- C.1 Status of Knowledge of Combustion Phenomena.- C.2 Methods of Reducing Natural Convection.- C.2.1 Miniaturization.- C.2.2 Reduction of Density Differences.- C.2.3 Reduced Gravity.- D. Applications of Microgravity.- D.1 General Interest.- D.2 Droplet Combustion Under Microgravity.- D.3 Flame Spread Along Solid Surfaces.- E. Concluding Remarks.- F. References.- II. Materials Science.- Crystal Growth.- X. Crystal Growth from the Melt.- A. Introduction.- B. Terrestrial Technology and Its Gravity-Related Limitations.- B.1 Current Growth Techniques.- B.2 Chemical and Structural Imperfections.- B.2.1 Introduction.- B.2.2 Gravity-Induced Imperfections.- B.2.3 Non-Gravity-Induced Imperfections.- C. Fundamental Aspects.- C.1 Introduction.- C.2 Buoyancy-Driven Convection.- C.2.1 Steady Buoyancy-Driven Flows.- C.2.2 Transition to New Flows.- C.2.3 Time-Dependent Convection.- C.2.4 Effect of a Magnetic Field.- C.3 Marangoni Flows.- C.3.1 Introduction.- C.3.2 Flow in Floating Zones.- C.3.3 Marangoni-Buoyancy Instability in Microgravity.- C.4 Response of the Crystal/Melt Interface.- C.4.1 Generation of Solute Striatums.- C.4.2 Morphological-Convective Instabilities.- D. Potential of Microgravity.- D.1 Unique Characteristics of Microgravity.- D.1.1 Absence of Buoyancy-Driven Convection.- D.1.2 The Absence of Hydrostatic Pressure.- D.2 A New Research Environment: Fields of Interest.- D.2.1 Basic Research: Verification of Theoretical Models.- D.2.2 Accurate Measurements of Materials Parameters.- D.2.3 Investigation of Gravity-Masked Effects.- D.2.4 Development of Space-Relevant Growth Techniques.- D.2.5 Preparation of Research Samples.- E. Results of Space Experiments.- E.1 Introduction.- E.2 Reduction of the Number of Structural Defects.- E.2.1 Decreased Dislocation Densities.- E.2.2 Reduction in the Number of Twins and Grain Boundaries.- E.2.3 Improved Single Crystallinity.- E.3 Chemical Macro-homogeneity.- E.4 Chemical Micro-homogeneity.- E.5 Solute Segregation by (Time-Dependent) Marangoni Flows.- E.5.1 Persistence of Striations in Float-Zoned Silicon.- E.5.2 Suppression of Striations by Surface-Coating.- E.5.3 Float-Zoning of Germanium.- E.5.4 Striations in Wall-Free Solidified Indium Antimonide.- E.6 Experience with Containerless Crystallisation.- E.6.1 Seeded Solidification of Drops.- E.6.2 Float-Zone Crystallization.- F. Future Aspects.- F.1 Introduction.- F.2 Future Scientific Activities.- F.2.1 Materials.- F.2.2 Subjects for Basic Research.- F.2.3 Development of Novel Growth Techniques.- F.2.4 Growth of Samples for Earthbound Research and Technology.- F.3 Research Policy.- F.4 Equipment.- F.4.1 General.- F.4.2 Automatization of Crystal Growth Experiments.- G. References.- XI. Crystal Growth from the Vapour Phase.- A. Introduction.- B. Physical Vapour Transport (PVT), Theoretical Background.- B.1 Nucleation and Growth Kinetics.- B.1.1 Supersaturation.- B.1.2 Continuous Growth and Film Deposition.- B.1.3 Lateral Growth.- B.2 Mass Transport.- B.2.1 Diffusive Transport in Cylindrical Ampoules — Advective Flow.- B.2.2 Free Convection in Cylindrical Ampoules.- B.2.3 Interplay Between Surface Kinetics and Transport.- C. Experimental Investigation.- C.1 Mass Transport.- C.1.1 Introduction.- C.1.2 Partial Pressures of Impurities in Closed Ampoules.- C.2 Ground-Based Vapour Growth Studies: Model Substance ?-HgI2.- C.2.1 Growth Rates.- C.2.2 Growth Rate and Crystal Habit as a Function of Orientation.- C.3 Vapour Growth Experiments Performed in Space.- D. Potential Future Experiments Under Microgravity Conditions.- E. Conclusions and Recommendations.- F. References.- XII. Crystal Growth from Solutions.- A. Introduction.- B. Fundamentals — Convective Phenomena in Solution Growth.- B.1 Introduction.- B.1.1 Solid-Liquid Interface.- B.1.2 Hydrodynamics.- B.1.3 Transport Phenomena.- C. High Temperature Solution Growth.- C.1 Crystal Growth from Non-Metallic Solutions (Flux Growth).- C.1.1 Experimental Arrangements.- C.1.2 Characterization.- C.1.3 Conclusions.- C.2 Growth of Electronic Materials from Metallic Solutions.- C.2.1 Basic Considerations.- C.2.2 THM Growth of Binary III-IV Semiconductors in Space.- C.2.3 Growth of Binary and Ternary II-VI Compounds in Space.- C.2.4 Conclusions.- D. Low Temperature Solution Growth.- D.1 Introduction.- D.2 Low Solubility Materials.- D.2.1 Basic Considerations.- D.2.2 Space Experiments.- D.2.3 Discussion.- D.3 High Solubility Materials.- D.3.1 Basic Considerations.- D.3.2 Space Experiments.- D.3.3 Discussion.- D.4 Conclusions.- E. Conclusions.- E.1 Past Results.- E.2 Definition of Space Experiments.- E.3 Choice of Samples.- E.4 Future Aspects.- E.4.1 Short Range.- E.4.2 Medium and Long Range.- F. References.- XIII. Crystal Growth of Biological Materials.- A. Introduction.- B. Why Is It Important to Crystallize Biological Materials?.- B.1 Why Do We Want to Know a Biological Structure?.- B.2 X-ray Diffraction and Crystallization.- B.3 A Selection of Structural Results Obtained so Far Using Structural Analysis and Potential Applications.- B.4 Summary.- C. The Tools of Protein Crystallography.- C.1 Synchrotron Radiation.- C.2 Detectors.- C.3 Neutron Sources.- C.4 Computers.- C.5 Summary.- D. Protein Crystallization on Earth.- D.1 The Principle.- D.1.1 Decrease of the Protein Solubility.- D.1.2 Repulsive and Attractive Forces.- D.1.3 Summary of the Variable Factors in Protein Crystallization Experiments.- D.2 Practical Considerations.- E. Microgravity.- E.1 European Single Crystal Growth Experiments with Proteins Under Microgravity Conditions.- E.2 Single Crystal Growth Microgravity Experiments by NASA.- E.2.1 Advantages of Space Outlined for Protein Crystal Growth.- E.2.2 Protein Crystallization Techniques for Space Experiments.- E.2.3 Details of Hardware Design.- E.2.4 Results.- E.2.5 Summary.- F. Assessment of Crystal Quality.- G. Recommendations.- H. References.- Alloys, Composites and Glasses.- XIV. Metals and Alloys.- A. Introduction.- B. The Undercooled Melt and Nucleation.- B.1 General Considerations.- B.2 Fundamental Aspects.- B.3 Links to Applications.- C. Theory of Solidification.- C.1 Interface Conditions.- C.2 Heat and Solute Transport.- C.3 Morphological Stability.- C.4 Isolated Dendrites.- C.5 Array Growth (Cells and Dendrites).- C.5.1 Cellular Growth.- C.5.2 Dendrite Arrays.- C.6 Eutectic Growth.- C.6.1 Regular Structures.- C.6.2 Irregular Eutectics.- C.7 Ripening.- C.8 Particle Pushing or Engulfment.- D. Convective Effects During Solidification of Metals and Alloys.- D.1 Solidification in the Presence of Driving Forces for Convection Outside the Solutal Boundary Layer.- D.1.1 Thermal Convection in the Bulk.- D.1.2 Cellular Growth in Alloys of Low Concentration.- D.1.3 Eutectic Solidification.- D.1.4 Marangoni Convection During Solidification.- D.2 Solidification in the Presence of Driving Forces for Convection Inside the Solutal Boundary Layer.- D.2.1 Planar Front Solidification and Cellular Growth of Concentrated Alloys.- D.2.2 Dendritic Solidification.- E. Main Results of Solidification Experiments in Space.- E.1 Casting.- E.2 Directional Solidification.- E.2.1 Macrosegregation and Morphological Stability.- E.2.2 Dendritic Growth.- F. Application-Oriented Research.- F.1 Materials Performance Improvements.- F.1.1 Superconductivity.- F.1.2 Magnetic Properties.- F.1.3 Mechanical Hardening.- F.2 Future Application-Oriented Research.- F.2.1 Dispersions.- G. Quantitative Investigation of Solidification.- G.1 “GETS” Experiment.- G.2 The Mephisto Project.- H. Conclusions.- I. References.- XV. Systems with a Miscibility Gap in the Liquid State.- A. Introduction.- B. Fundamentals.- B.1 Thermodynamics.- B.1.1 Basic Considerations.- B.1.2 Empirical Relationships and Evaluation Possibilities.- B.2 Atomistic Theory.- B.2.1 Influence of the Difference of the Atomic Radii.- B.2.2 Application of the Model Concept Concerning the Influence of Atomic Radii Differences.- B.2.3 Miscibility Gaps in Systems with Negative ?H Values.- B.3 Various Types of Miscibility Gap Phase Diagrams.- B.4 Ternary Systems.- C. Kinetics of Phase Separation.- C.1 Nucleation.- C.2 Growth.- C.3 Collisions, Coagulation and Coalescence.- D. Experiments on Immiscibles.- D.1 Studies on Nucleation.- D.2 Investigations on Growth Processes.- D.3 Coalescence and Coagulation.- E. Future Perspectives.- E.1 Scientific Perspectives.- E.2 Materials for Applications.- F. References.- XVI. Composites.- A. Introduction.- A.1 Definition.- A.2 The Relevance of Microgravity to Research on Composites.- A.3 Applications.- B. In Situ Composites.- B.1 Eutectics.- B.1.1 Influence of Convection on the Microstructure of Unidirectionally Solidified Eutectic Alloys.- B.1.2 Results of Microgravity Experiments.- B.1.3 Conclusions.- B.2 Peritectic Solidification.- B.2.1 Experimental Results.- B.2.2 Conclusions.- B.3 Monotectics.- B.3.1 Experimental Results.- B.3.2 Conclusions.- C. Artificial Composites.- C.1 Particle and Fibre Composites.- C.1.1 Stability of Particle Dispersions.- C.1.2 Experimental Results.- C.1.3 Conclusions.- C.2 Materials with Controlled Density.- C.2.1 Principles of Foam Generation.- C.2.2 Experimental Results.- C.2.3 Conclusions.- D. Discussion and Recommendations.- D.1 General Remarks.- D.2 Basic Research Topics.- D.2.1 In Situ Composites.- D.2.2 Artificial Composites.- D.3 Practical Aspects for Microgravity Experimentation.- E. Conclusions and Outlook.- F. References.- XVII. Glasses.- A. Introduction.- B. Glass Formation.- B.1 Introduction.- B.1.2 Nucleation.- B.1.3 Crystal Growth.- B.1.4 Temperature-Time Transformation Diagrams.- C. Glass-Forming Systems.- C.1 Nonmetallic Systems.- C.2 Metallic Systems.- C.3 Microgravity Aspects.- C.3.1 Nucleation Studies and Formation of Metallic Glasses.- C.3.2 Preparation of Nonmetallic Glasses.- D. Experimental Facilities.- D.1 Required Facilities.- D.2 Available Facilities.- D.2.1 Conventional Systems.- D.2.2 Levitation Systems.- E. Review of Achievements to Date.- E.1 Metallic Systems.- E.1.1 Nucleation Studies on Earth.- E.1.2 Microgravity Experiments.- E.2 Nonmetallic Systems.- E.2.1 Ground-Based Investigations.- E.2.2 Flight Experiments.- F. Conclusions and Recommendations.- G. References.- Analysis of the Limitations of Microgravity and Applications.- XVIII. Influence of Residual Accelerations on Fluid Physics and Materials Science Experiments.- A. Introduction.- B. General Considerations on g-Tolerability.- B.1 Definition of Tolerable g-Levels.- B.2 Objectives of the g-Tolerability Analysis.- B.3 The Set of Relevant Equations.- B.4 Order of Magnitude Analysis (OMA).- B.5 Application of OMA to g-Level Tolerability Problems.- C. Review of Past Activities in Fluid Science.- C.1 Thermo-Fluid-Dynamic and Sedimentation Phenomena.- C.2 Liquid Specimen Response to g-Level Disturbances.- D. Analysis of Specific Problems.- D.1 Crystal Growth from the Melt.- D.1.1 Description of the Problem.- D.1.2 Fluid Dynamics Modelling: Steady-State Conditions.- D.1.3 Segregation Behaviour.- D.1.4 TFD Modelling in Non-Steady-State Conditions: g-Jitter.- D.1.5 Segregation Behaviour as a Result of g-Jitter.- D.2 Growth from Solutions.- D.2.1 Growth at Low Peclet Numbers.- D.2.2 Growth Anisotropy in a Gravity Field.- D.2.3 Solutal Instabilities.- D.3 Oscillations of Liquid Columns.- D.3.1 Stability and Breakage.- D.3.2 Resonance Frequencies.- D.3.3 Reduction of the Tolerable g-Levels by Resonant Modes.- D.4 Diffusion and Thermodiffusion Experiments.- D.4.1 Description of the Problem.- D.4.2 Self- and Interdiffusion.- D.4.3 Thermodiffusion.- E. Conclusions and Recommendations.- F. References.- XIX. Industrial Potential of Microgravity.- A. Introduction.- B. Present Status.- B.1 U.S.A.- B.2 U.S.S.R.- B.3 Japan.- B.4 Europe.- B.4.1 Germany.- B.4.2 France.- B.4.3 Other European Countries.- C. Potential of Materials Processing in Space.- C.1 Introduction.- C.2 Economic Considerations.- C.3 Glasses.- C.4 Crystal Growth from the Melt.- C.5 Crystal Growth from the Vapour Phase.- C.6 Crystallization of Inorganic Materials from Solutions.- C.7 Protein Crystallization.- C.8 Microgravity-Adapted Processes.- D. Discussion.- E. Recommendations for a European Policy.- F. References.- Index of Contributors.