<p>Particle suspensions in viscoelastic fluids (e.g., polymeric fluids, liquid crystalline solutions, gels) are ubiquitous in industrial processes and in biology. In such fluids, particles often acquire lift forces that push them to preferential streamlines in the flow domain. This lift force depends greatly on the fluid’s rheology, and plays a vital role in many applications such as particle separations in microfluidic devices, particle rinsing on silicon wafers, and particle resuspension in enhanced oil recovery. Previous studies have provided understanding on how fluid rheology affects the motion of spherical particles in simple viscoelastic fluid flows such as shear flows. However, the combined effect of more complex flow profiles and particle shape is still under-explored. The main contribution of this thesis is to: (a) provide understanding on the migration and rotation dynamics of an arbitrary-shaped particle in complex flows of a viscoelastic fluid, and (b) develop guidelines for designing such suspensions for general applications.</p> <p><br></p> <p>In the first part of the thesis, we develop theories based on the second-order fluid (SOF) constitutive model to provide solutions for the polymeric force and torque on an arbitrary-shaped solid particle under a general quadratic flow field. When the first and second normal stress coefficients satisfy  <strong>Ψ</strong>₁  = −2 <strong>Ψ</strong> ₂ (corotational limit), the fluid viscoelasticity modifies only the fluid pressure and we provide exact solutions to the polymer force and torque on the particle. For a general SOF with  <strong>Ψ</strong> ₁ ≠  −2 <strong>Ψ</strong> ₂, fluid viscoelasticity modifies the shear stresses, and we provide a procedure for numerical solutions. General scaling laws are also identified to quantify the polymeric lift based on different particle shapes and orientation. We find that the particle migration speed is directly proportional to the length the particle spans in the shear gradient direction (L_sg), and that polymeric torques lead to unique orientation behavior under flow.</p> <p><br></p> <p>Secondly, we investigate the migration and rotational behavior of prolate and oblate spheroids in various viscoelastic, pressure-driven flows. In a 2-D slit flow, fluid viscoelasticity causes prolate particles to transition to a log-rolling motion where the particles orient perpendicular to the flow-flow gradient plane. This behavior leads to a slower overall migration speed (i.e., lift) of prolate particles towards the flow centerline compared to spherical particles of the same volume. In a circular tube flow, prolate particles align their long axis along the flow direction due to the extra polymer torque generated by the velocity curvature in all radial directions. Again, this effect causes prolate particles to migrate slower to the flow centerline than spheres of the same volume. For oblate particles, we quantify their long-time orientation and find that they migrate slower than spheres of the same volume, but exhibit larger migration speeds than prolate particles. Lastly, we examine the effect of normal stress ratio ? <strong>α</strong>  = <strong>Ψ</strong> ₂ /<strong>Ψ</strong>₁on the particle motion and find that this parameter only quantitatively impacts the particle migration velocity but has negligible effect on the rotational dynamics. We therefore can utilize the exact solution derived under the corotational limit (?<strong>α</strong> = −1/2) for a quick and reasonable prediction on the particle dynamics.</p> <p><br></p> <p>We next experimentally investigate the migration behavior of spheroidal particles in microfluidic systems and draw comparisons to our theoretical predictions. A dilute suspension of prolate/oblate microparticles in a density-matched 8% aqueous polyvinylpyrrolidone (PVP) solution is used as the model suspension system. Using brightfield microscopy, we qualitatively confirm our theoretical predictions for flow Deborah numbers 0 < De < 0.1 – i.e., that spherical particles show faster migration speed than prolate and oblate particles of the same volume in tube flows.</p> <p><br></p> <p>We finally design a holographic imaging method to capture the 3-D position and orientation of dynamic microparticles in microfluidic flow. We adopt in-line holography setup and propose a straightforward hologram reconstruction method to extract the 3-D position and orientation of a non-spherical particle. The method utilizes image moment to locate the particle and localize the detection region. We detect the particle position in the depth direction by quantifying the image sharpness at different depth position, and uses principal component analysis (PCA) to detect the orientation of the particle. For a semi-transparent particle that produces complex diffraction patterns, a mask based on the image moment information can be utilized during the image sharpness process to better resolve the particle position.</p> <p><br></p> <p>In the last part of this thesis, we conclude our work and discuss the future research perspectives. We also comment on the possible application of current work to various fields of research and industrial processes.</p> <p><br></p>

In der vorliegenden Arbeit wird eine Methodik zur Entwicklung mechanischer Simulationen der Interaktion Sportler-Sportgerät-Umwelt zur Untersuchung der Funktionalität von Sportgeräten konzipiert und vorgestellt. Die mechanische Simulation ist die gegenständliche Nachbildung spezieller Teilaspekte des Sportlers, z.B. der Körperform, der Trägheitseigenschaften, der Masse, der Interaktionskräfte zur Umwelt oder charakteristischer Bewegungsabläufe zum Zweck der Durchführung gezielter Experimente zur Untersuchung des dynamischen Systemverhaltens Sportler-Sportgerät-Umwelt. Dazu werden drei Fallbeispiele aus der Forschungstätigkeit der Arbeitsgruppe HLST an der Technischen Universität Chemnitz mit Methoden zur Verifikation von Simulationsmodellen – dem strukturierten Durchgehen, der Validierung im Dialog und dem Schreibtischtest – analysiert. Die Analyseergebnisse werden in eine Grobstruktur eingebettet, die aus relevanten Vorarbeiten zur Anwendung der Allgemeinen Modelltheorie abgeleitet ist. Die in den jeweiligen Fallbeispielen verwendeten Prozessschritte, Methoden und Werkzeuge werden dargestellt und die Entwicklungsergebnisse erörtert. Im Abschluss jedes Fallbeispiels wird der Entwicklungsprozess anhand von einheitlichen Kriterien bewertet. In einem abschließenden Schritt erfolgt die Zusammenführung der im Stand der Technik dargelegten Grundlagen und der in den drei Fallbeispielen gewonnenen Informationen zu einer strukturieren und kommentierten Methodik.:1 Einleitung 8 1.1 Definitionen 8 1.2 Einsatzgebiete der mechanischen Simulation 11 1.2.1 Überblick 11 1.2.2 Sicherheit gegen Versagen 12 1.2.3 Konformität 14 1.2.4 Funktionalität 15 1.3 Motivation und Zielsetzung 16 1.4 Aufbau der Arbeit 16 2 Theoretische Grundlagen 18 2.1 Experimentelle Methoden der Sportgeräteentwicklung 18 2.1.1 Einordnung nach Odenwald (2006) 18 2.1.2 Einordnung nach Witte (2013) 19 2.1.3 Einordnung nach Senner (2001) 20 2.1.4 Eigene Systematisierung 23 2.2 Allgemeine Modelltheorie 26 2.3 Existierende Ansätze für die Applikation der Allgemeinen Modelltheorie 29 2.3.1 Anwendung der AMT in der Chemie 29 2.3.2 Anwendung der AMT in der Biomechanik 30 2.3.3 Anwendung der AMT in Logistik und Produktion 32 2.3.4 Fazit 37 3 Präzisierung der Problemstellung 38 4 Methodik 39 5 Fallbeispiel Schwimmanzug – Strömungswiderstand 41 5.1 Vorbemerkungen 41 5.2 Aufgabenanalyse 42 5.2.1 Definition der zu untersuchenden Funktionalität des Sportgeräts 42 5.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 42 5.2.3 Analyse der Simulationswürdigkeit 43 5.2.4 Identifikation des Originals 47 5.3 Modellformulierung 48 5.3.1 Modellansatz 48 5.3.2 Modellsynthese 50 5.4 Modellimplementierung 53 5.4.1 Herstellung des Strömungskörpers 53 5.4.2 Simulation der Fortbewegung im Wasser 54 5.5 Modellanwendung 57 5.6 Modellüberprüfung 60 5.6.1 Abgleich zwischen den experimentellen Ergebnissen und dem theoretischen Modell 60 5.6.2 Vergleich mit dem Original 62 5.7 Fazit 67 6 Fallbeispiel Laufschuh – Stoßabsorption 69 6.1 Vorbemerkungen 69 6.2 Aufgabenanalyse 69 6.2.1 Definition der zu untersuchenden Funktionalität 69 6.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 71 6.2.3 Analyse der Simulationswürdigkeit 71 6.2.4 Definition des Originals 72 6.3 Modellformulierung 72 6.3.1 Modellansatz 72 6.3.2 Systemanalyse 72 6.3.3 Modellsynthese 77 6.4 Modellimplementierung 78 6.4.1 Krafterzeugung 78 6.4.2 Kraftübertragung 79 6.5 Modellanwendung 81 6.6 Modellüberprüfung 82 6.6.1 Soll-Istwert-Vergleich 82 6.6.2 Reliabilität 83 6.6.3 Korrelation zu Stoßbelastungsvariablen 85 6.6.4 Ereignisvaliditätstest: Sohlentemperatur 86 6.6.5 Ereignisvaliditätstest: Sohlendeformation 88 6.7 Fazit 91 7 Fallbeispiel Fußballschuh – Traktionseigenschaften 94 7.1 Vorbemerkungen 94 7.2 Aufgabenanalyse 94 7.2.1 Definition der zu untersuchenden Funktionalität 94 7.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 95 7.2.3 Analyse der Simulationswürdigkeit 96 7.2.4 Definition des Originals 97 7.3 Modellformulierung 98 7.3.1 Modellansatz 98 7.3.2 Systemanalyse 98 7.3.3 Modellsynthese 106 7.4 Modellimplementierung 107 7.5 Modellanwendung 110 7.6 Modellüberprüfung 114 7.6.1 Reliabilität 114 7.6.2 Sensitivitätsanalyse: Normalkraft 114 7.6.3 Sensitivitätsanalyse: Kraftanstieg horizontal 116 7.6.4 Vergleich mit der Realität 116 7.7 Fazit 117 8 Methodik zur Entwicklung mechanischer Simulationen der Interaktion Sportler-Sportgerät-Umwelt 119 8.1 Schematische Darstellung 119 8.2 Erläuterung der Vorgehensempfehlung 120 8.2.1 Klärung der Problemstellung 120 8.2.2 Modellbildung 122 8.2.3 Modellanwendung 124 9 Schlussbetrachtung 126 Literaturverzeichnis 128 Tabellenverzeichnis 133 Abbildungsverzeichnis 135 Danksagung 138 Selbstständigkeitserklärung 139 Lebenslauf 140 / In this dissertation a methodology is conceived that aims to structure the development process of test arrangements that mechanically simulate the interaction of athlete, sports equipment and environment. Mechanical simulation in this context is defined as the physical replication of specific properties of the athlete (e.g. the shape of the human body, body weight, joint kinematics, inertia, external forces in specific movements) in order to conduct experiments to investigate the dynamic behavior of the system athlete-equipment-environment. Therefore, three case studies of mechanical simulation models that have been developed at Technische Universität Chemnitz are analyzed by applying the validation and verification methods “structured walkthrough”, “face validity” and “desk checking”. The results of that analysis are embedded into a framework that is derived by literature review on applied model theory. For each of the three development processes the procedure model is identified and main tools and methods are discussed. Every case study is finally assessed by using standardized evaluation criterions. Finally, the main findings of the analysis of the case studies as well as knowledge obtained by reviewing the state of the art in model theory and simulation methods are used to build up a structured and commentated guideline.:1 Einleitung 8 1.1 Definitionen 8 1.2 Einsatzgebiete der mechanischen Simulation 11 1.2.1 Überblick 11 1.2.2 Sicherheit gegen Versagen 12 1.2.3 Konformität 14 1.2.4 Funktionalität 15 1.3 Motivation und Zielsetzung 16 1.4 Aufbau der Arbeit 16 2 Theoretische Grundlagen 18 2.1 Experimentelle Methoden der Sportgeräteentwicklung 18 2.1.1 Einordnung nach Odenwald (2006) 18 2.1.2 Einordnung nach Witte (2013) 19 2.1.3 Einordnung nach Senner (2001) 20 2.1.4 Eigene Systematisierung 23 2.2 Allgemeine Modelltheorie 26 2.3 Existierende Ansätze für die Applikation der Allgemeinen Modelltheorie 29 2.3.1 Anwendung der AMT in der Chemie 29 2.3.2 Anwendung der AMT in der Biomechanik 30 2.3.3 Anwendung der AMT in Logistik und Produktion 32 2.3.4 Fazit 37 3 Präzisierung der Problemstellung 38 4 Methodik 39 5 Fallbeispiel Schwimmanzug – Strömungswiderstand 41 5.1 Vorbemerkungen 41 5.2 Aufgabenanalyse 42 5.2.1 Definition der zu untersuchenden Funktionalität des Sportgeräts 42 5.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 42 5.2.3 Analyse der Simulationswürdigkeit 43 5.2.4 Identifikation des Originals 47 5.3 Modellformulierung 48 5.3.1 Modellansatz 48 5.3.2 Modellsynthese 50 5.4 Modellimplementierung 53 5.4.1 Herstellung des Strömungskörpers 53 5.4.2 Simulation der Fortbewegung im Wasser 54 5.5 Modellanwendung 57 5.6 Modellüberprüfung 60 5.6.1 Abgleich zwischen den experimentellen Ergebnissen und dem theoretischen Modell 60 5.6.2 Vergleich mit dem Original 62 5.7 Fazit 67 6 Fallbeispiel Laufschuh – Stoßabsorption 69 6.1 Vorbemerkungen 69 6.2 Aufgabenanalyse 69 6.2.1 Definition der zu untersuchenden Funktionalität 69 6.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 71 6.2.3 Analyse der Simulationswürdigkeit 71 6.2.4 Definition des Originals 72 6.3 Modellformulierung 72 6.3.1 Modellansatz 72 6.3.2 Systemanalyse 72 6.3.3 Modellsynthese 77 6.4 Modellimplementierung 78 6.4.1 Krafterzeugung 78 6.4.2 Kraftübertragung 79 6.5 Modellanwendung 81 6.6 Modellüberprüfung 82 6.6.1 Soll-Istwert-Vergleich 82 6.6.2 Reliabilität 83 6.6.3 Korrelation zu Stoßbelastungsvariablen 85 6.6.4 Ereignisvaliditätstest: Sohlentemperatur 86 6.6.5 Ereignisvaliditätstest: Sohlendeformation 88 6.7 Fazit 91 7 Fallbeispiel Fußballschuh – Traktionseigenschaften 94 7.1 Vorbemerkungen 94 7.2 Aufgabenanalyse 94 7.2.1 Definition der zu untersuchenden Funktionalität 94 7.2.2 Analyse der zugrundeliegenden technischen Funktion des Sportgeräts 95 7.2.3 Analyse der Simulationswürdigkeit 96 7.2.4 Definition des Originals 97 7.3 Modellformulierung 98 7.3.1 Modellansatz 98 7.3.2 Systemanalyse 98 7.3.3 Modellsynthese 106 7.4 Modellimplementierung 107 7.5 Modellanwendung 110 7.6 Modellüberprüfung 114 7.6.1 Reliabilität 114 7.6.2 Sensitivitätsanalyse: Normalkraft 114 7.6.3 Sensitivitätsanalyse: Kraftanstieg horizontal 116 7.6.4 Vergleich mit der Realität 116 7.7 Fazit 117 8 Methodik zur Entwicklung mechanischer Simulationen der Interaktion Sportler-Sportgerät-Umwelt 119 8.1 Schematische Darstellung 119 8.2 Erläuterung der Vorgehensempfehlung 120 8.2.1 Klärung der Problemstellung 120 8.2.2 Modellbildung 122 8.2.3 Modellanwendung 124 9 Schlussbetrachtung 126 Literaturverzeichnis 128 Tabellenverzeichnis 133 Abbildungsverzeichnis 135 Danksagung 138 Selbstständigkeitserklärung 139 Lebenslauf 140

<p>Two studies incorporated providing the groundwork for a blueprint to design sodium sulfur cells from electrode fabrication to choices in electrolyte such as DME, DEGDME, TEGDME and two different salts NaClO4 and NaPF6. First study describes role of the binder within the system comparing carboxymethyl cellulose and carboxymethyl cellulose with a styrene butadiene elastomer addition. The second study focuses on methods to prevent polysulfide shuttling within room temperature sodium sulfur system</p>

<p> Wire-wrapped rod bundles are often used in nuclear reactors operating in a fast neutron spectrum, as designers seek to minimize neutron scattering by packing the fuel pins into a hexagonal lattice. Bundles with many rods have extensively been studied as representative of large fuel assemblies, however far fewer experiments have investigated bundles with 7 rods (7-pin bundles). The large difference in subchannel number between these bundles leads to 7-pin bundles having different pressure drop characteristics. The Versatile Test Reactor (VTR) sodium cartridge loop proposes to use a 7-pin bundle as its experimental core region, highlighting the need for additional data and models. The current work seeks to establish a better understanding of the pressure drop in 7-pin wire-wrapped rod bundles through scaled experiments and a novel pressure drop model. A scaling analysis is first performed to demonstrate the applicability of water experiments to the VTR sodium cartridge loop, before an experimental test facility is designed and constructed. Experiments are then performed at a range of Reynolds numbers to determine the pressure drop. Current models are able to predict the data well, but are complex and can be difficult to use. A comparatively simpler model is developed, based on exact laminar solutions of a simplified rod bundle, which also offers a theoretical lower bound for the pressure drop in wire-wrapped bundles. The proposed model compares well with the existing experimental database, able to predict bundle friction factor with an average absolute percent difference of 10.8%. This accuracy is also similar to existing correlations, while relying on fewer empirical coefficients. The theoretical lower bound is also used to identify several datasets in literature that may feature data that is systemically lower than the true pressure drop, which agrees with previous observations in literature. </p>

<p>Future long-duration space missions will take humans farther from the support resources of Earth than ever before. These missions will require microgravity surgical technologies in the case of an emergency that necessitates medical intervention. This experiment integrated three different surgical technologies for testing in weightlessness on parabolic flights: a surgical containment dome, a multi-function surgical wand, and a microgravity blood-air separator. Two fluid loops were utilized: one in which the surgical wand, containment dome, and a wound model were used to provide a realistic mixture of blood simulant and air to the blood-air separator. The other fluid loop used prescribed mixture ratios of air and blood to test the performance of the separator under varying conditions. The results of this experiment showed that the multi-functional surgical tool and dome functioned as designed. In addition, each separator successfully separated the blood and air from the mixture, allowing for future blood transfusion. With this demonstration, each system used in this experiment qualifies as technology readiness level 6. Advancing the technology readiness level of these technologies further will require long duration zero-g testing on-orbit before inclusion in authentic space mission emergency surgical strategy. </p>

<p>  </p> <p>Water scarcity is a global problem impacting a majority of the world population. A significant proportion of the global population is deprived of clean drinking water, an impact felt by the rural as well as urban population. Saltwater desalination provides an attractive option to produce clean water. Some technologies to generate potable water include reverse osmosis (RO), multi-stage flash distillation (MSF), vapor compression distillation and multi-effect distillation (MED). Distillation plants such as those in MED often have falling-film evaporators operating at low energy conversion efficiency and hence distillation is performed over multiple stages (or effects). Porous materials can be utilized as evaporators in such plants with the objective of leveraging their superior efficiency. This can potentially decrease the number of effects over which distillation occurs. However, evaporation of high-salinity salt solution eventually results in salt precipitation which can cause fouling and induce structural damages, especially if the precipitates appear within the porous medium. Crystallization-induced structural damages are also of significant concern to building materials and for their role in weathering of historical monuments. It is thus crucial to understand the mechanisms governing salt precipitation in a porous medium.</p> <p>Transport of solute in such a medium is either driven by flow of the solution (advection) or by concentration gradients (diffusion). The dynamics of solute transport is further complicated due to the involvement of a reaction term accounting for any salt precipitation. The relative strengths of these driving forces determine the solute transport behavior during an evaporation-driven process. The wide-scale applications of solute transport and its complicated nature warrant investigation, both experimental and theoretical, of the dependence of solute transport and the subsequent precipitation on the operating conditions and the properties of the porous medium.</p> <p>This dissertation first focuses on developing a novel modeling framework for evaluating the transient behavior of the solute mass fraction profile within the domain of a one-dimensional porous medium, and extending its capability to predict the formation of salt precipitate in the medium.  Experimental investigations are then performed to study the formation of precipitate on sintered porous copper wicks of different particle-size compositions, and developing a mechanistic understanding of the governing principles.</p> <p>A numerical modeling framework is developed to analyze evaporation-driven solute transport. Transient advection-diffusion equations govern the salt mass fraction profile of the solution inside the porous medium. These governing equations are solved to obtain the solute mass fraction profile within the porous medium as well as the effloresced salt crust. Further accounting for precipitation allows a study of the formation and growth of efflorescence and subflorescence. Crystallization experiments are performed by allowing a NaCl solution to evaporate from a porous medium of copper particles and the subflorescence trends predicted by the model are validated. The modeling framework offers a comprehensive tool for predicting the spatio-temporal solute mass fraction profiles and subsequent precipitation in a porous medium.</p> <p>The dependence of efflorescence pattern on the properties of a porous medium is also investigated. Efflorescence patterns are visually observed and characterized on sintered copper particle wicks with spatially unimodal and bimodal compositions of different particle sizes. Efflorescence is found to form earlier and spread readily over a wick made from smaller particles, owing to their lower porosity, while it is limited to certain areas of the surface for wicks composed of the larger particles. A scaling analysis explains the observed efflorescence patterns in the bimodal wicks caused by particle size-induced non-uniform porosity and permeability. The non-uniformity reduces the advective flux in a high-permeability region by diverting flow towards a low-permeability region. This reduction in advective flux manifests as an exclusion distance surrounding a crystallization site where efflorescence is not expected to occur. The dependence of this exclusion distance on the porosity and permeability of the porous medium and the operating conditions is investigated. A large exclusion distance associated with the regions with bigger particles in the bimodal wicks explains preferential efflorescence over the regions with smaller particles. This novel scaling analysis coupled with the introduction of the exclusion distance provides guidelines for designing heterogeneous porous media that can localize efflorescence.</p> <p>Additionally, droplet interactions with microstructured superhydrophobic surfaces as well as soft surfaces were investigated during the course of this dissertation, separate from the above investigations. These investigations involve the interplay of surface energies with electrical or elastic energies and are studied both experimentally and through theoretical models, and therefore are retained as additional chapters in the thesis as being of relevant interest.  Electrowetting experiments are performed on superhydrophobic surfaces with re-entrant structures to study their resilience to the Cassie-to-Wenzel transition. The deformation of soft surfaces caused by forces exerted by microscale droplets is studied and the resulting interaction between multiple droplets is explored. </p>

The final thesis is focused od the experimental metods in energy rating of building. In the first part is described history of energy rating from the eigtheens to the present and described is the current trend of energy rating in terms of energy performance certificates. In the second part is elaborated energy assessment for apartment building from bricks with six residential units. For the building is drawn a total of 6 measures, of which there are 3 structural and 3 for building equipment. The measures are assembled to variants and the resulting variant is recommended, including recommendation. In the last experimental part is described the influence of shading elements on the thermal load of the room and modeled the effect of insulating double glazing and triple the overall energy performance reference room.

<p dir="ltr">Positive displacement machines are used in various industries spanning the power spectrum, from industrial robotics to heavy construction equipment to aviation. These machines should be highly efficient, compact, and reliable. It is very advantageous for designers to use virtual simulations to design and improve the performance of these units as they significantly reduce cost and downtime. The recent trends of electrification and the goal to increase power density force these units to work at higher pressures and higher rotational speeds while maintaining their efficiencies and reliability. This push means that the simulation models need to advance to account for various aspects during the operation of these machines. </p><p dir="ltr">These machines typically have several bodies in relative motion with each other. Quantifying these motions and solving for their effect on the fluid enclosed are vital as they influence the machine's performance. The push towards higher rotational speeds introduces unwanted cavitation and aeration in these units. To model these effects, keeping the design evaluation time low is key for a designer. The lumped parameter approach offers the benefit of computational speed, but a major drawback that comes along with it is that it typically assumes fluid inertia to be negligible. These effects cannot be ignored, as quantifying and making design considerations to negate these effects can be beneficial. Therefore, this thesis addresses these key challenges of cavitation dynamics, body dynamics, and accounting for fluid inertia effects using a lumped parameter formulation.</p><p dir="ltr">To account for dynamics features related to cavitation, this thesis proposes a novel approach combining the two types of cavitation, i.e., gaseous and vaporous, by considering that both vapor and undissolved gas co-occupy a spherical bubble. The size of the spherical bubble is solved using the Rayleigh-Plesset equation, and the transfer of gas through the bubble interface is solved using Henry's Law and diffusion of the dissolved gas in the liquid. These equations are coupled with a novel pressure derivative equation. To account for body dynamics, this thesis introduces a novel approach for solving the positions of the bodies of a hydraulic machine while introducing new methods to solve contact dynamics and the application of Elasto Hydrodynamic Lubrication (EHL) friction at those contact locations. This thesis also proposes strategies to account for fluid inertia effects in a lumped parameter-based approach, taking as a reference an External Gear Machine. This thesis proposes a method to study the effects of fluid inertia on the pressurization and depressurization of the tooth space volumes of these units. The approach is based on considering the fluid inertia in the pressurization grooves and inside the control volumes with a peculiar sub-division. Further, frequency-dependent friction is also modeled to provide realistic damping of the fluid inside these channels.</p><p dir="ltr">To show the validity of the proposed dynamic cavitation model, the instantaneous pressure of a closed fluid volume undergoing expansion/compression is compared with multiple experimental sources, showing an improvement in accuracy compared to existing models. This modeling is then further applied to a gerotor machine and validated with experiments. Integrating this modeling technique with current displacement chamber simulation can further improve the understanding of cavitation in hydraulic systems. Formulations for body dynamics are tested on a prototype Gerotor and Vane unit. For both gerotor and vane units, comparisons of simulation results to experimental results for various dynamic quantities, such as pressure ripple, volumetric, and hydromechanical efficiency for multiple operating conditions, have been done. Extensive validation is performed for the case of gerotors where shaft torque ripple and the motion of the outer gear is experimentally validated. The thesis also comments on the distribution of the different torque loss contributions. The model for fluid inertia effects has been validated by comparing the lumped parameter model with a full three-dimensional Navier Stokes solver. The quantities compared, such as tooth space volume pressures and outlet volumetric flow rate, show a good match between the two approaches for varying operating speeds. A comparison with the experiments supports the modeling approach as well. The thesis also discusses which operating conditions and geometries play a significant role that governs the necessity to model such fluid inertia effects in the first place.</p>