Hydromechanical Stress Research Articles

Impact of hydromechanical stress on CHO cells’ metabolism and productivity: Insights from shake flask cultivations with online monitoring of the respiration activity

The hydromechanical stress is a relevant parameter for mammalian cell cultivations, especially regarding scale-up processes. It describes the mechanical forces exerted on cells in a bioreactor. The maximum local energy dissipation rate is a suitable parameter to characterize hydromechanical stress. In literature, different studies deal with the effects of hydromechanical stress on CHO cells in stirred tank reactors. However, they often focus on lethal effects. Furthermore, systematic examinations in smaller scales like shake flasks are missing. Thus, this study systematically considers the influence of hydromechanical stress on CHO DP12 cells in shake flask cultivations. By utilizing online monitoring of the oxygen transfer rate, the study simplifies and enhances the resolution of examinations. Results indicate that while lethal effects are absent, numerous sub-lethal effects emerge with increasing hydromechanical stress: The process time is prolonged. The time of glucose and glutamine depletion, and the lactate switch correlate positively linear with the logarithmic average energy dissipation rate while the maximum specific growth rate correlates negatively. Strikingly, the final antibody concentration only declines at the highest tested average energy dissipation rate of 3.84Wkg-1 (only tested condition with a turbulent flow regime and therefore a higher maximal local energy dissipation rate) from about 250mgL-1 to about 180mgL-1. This study presents a straightforward method to examine the impact of hydromechanical stress in shake flasks, easily applicable to any other suspension cell line. Additionally, it offers valuable insights for scale-up processes, for example into stirred tank reactors.

A fully automated unsaturated triaxial device for testing of soils under complicated hydromechanical stress paths

A fully-automated unsaturated triaxial device is developed at the Advanced Soil Mechanic Laboratory of the Sharif University of Technology (SUT) to investigate the hydromechanical behavior of unsaturated soils under any complicated path. The main improvements of the developed device are (1) the ability to continuously measure accurately different stress/strain variables during long duration of unsaturated tests. This is of great importance in capturing the sudden deformations of the specimen, under wetting (2) providing a user-friendly controller software enabling the definition of any desired stress/strain variable and stress/strain paths under either stress-controlled or strain-controlled conditions. Finally, to evaluate the performance of the developed apparatus, two wetting tests were carried out to study the effect of initial shear stress on the hydromechanical behavior of unsaturated reconstituted specimens of Gorgan loess. In these wetting tests, the specimens were wetted under isotropic and anisotropic stress states by stepwise reduction of suction to approach to the saturated condition. The obtained results showed the excellent performance of the developed device to accurately follow the defined stress path along with the continuous measurement of stress/strain variables. The tested collapsible soil specimen that was wetted under the effect of initial shear stress exhibited a larger volume decrease accompanied by a larger degree of saturation compared to those of the specimen wetted under the isotropic stress state with the same initial mean net stress.

Compressibility and microstructure of kaolin in varying thermo-hydro-mechanical states imposed by energy geostructures

The thermal volumetric behaviour of soils plays a critical role in designing energy geostructures, withstanding temperature fluctuations. This study examined, for the first time, the thermal deformation of the partially saturated kaolin clay (matric suction of 0–300 kPa) within the operating temperature range of energy geostructures (8 °C to 45 °C), subjected to varying most recent stress histories (normal stress of 0–400 kPa). The thermal cycle has been applied to samples with identical hydro-mechanical stress histories initiated by heating or cooling from room temperature. Scanning electron microscopy (SEM) tests have been performed to investigate the impact of temperature on soil microstructure as a potential determining mechanism of thermal deformation. The volumetric deformation associated with thermal cycles is analysed, considering the concurrent role of the overconsolidation ratio and the most recent stress. Secondary thermal consolidation (i.e., particle rearrangement) mainly depends on the most recent stress history, occurring only in samples heated beyond the yield limit, with cooling preventing secondary thermal consolidation. A clear relationship between thermal volume change and matric suction was observed, with higher matric suction resulting in less pronounced particle rearrangement. Further SEM analysis revealed that heating beyond the yield limit alters the soil microstructure permanently, with cooling showing no impact.

Scale-up of an amoeba-based process for the production of the cannabinoid precursor olivetolic acid

BackgroundThe availability of new biological platform organisms to get access to innovative products and processes is fundamental for the progress in biotechnology and bioeconomy. The amoeba Dictyostelium discoideum represents a novel host system that has recently been employed for both the discovery of new natural products and as a cell factory for the production of bioactive compounds such as phytochemicals. However, an essential parameter to evaluate the potential of a new host system is the demonstration of its scalability to allow industrial applicability. Here, we aimed to develop a bioprocess for the production of olivetolic acid, the main precursor of cannabinoids synthesized by a recently engineered D. discoideum strain.ResultsIn this study, a sophisticated approach is described to scale-up an amoeba-based polyketide production process in stirred tank bioreactors. Due to the shear sensitivity of the cell wall lacking amoebae, the maximum local energy dissipation rate (εmax) was selected as a measure for the hydromechanical stress level among different scales. By performing 1.6-L scale batch fermentations with different stress conditions, we determined a maximum tolerable εmax of 3.9 W/kg for D. discoideum. Further, we used this parameter as scale-up criterion to develop a bioprocess for olivetolic acid production starting from a 7-L stirred tank reactor to the industrially relevant 300-L scale with a product concentration of 4.8 µg/L, a productivity of 0.04 µg/L/h and a yield of 0.56 µg/g glucose.ConclusionWe developed a robust and reliable scale-up strategy for amoeba-based bioprocesses and evaluated its applicability for the production of the cannabinoid precursor olivetolic acid. By determining the maximum tolerable hydromechanical stress level for D. discoideum, we were able to scale-up the process from shake flasks to the 300-L stirred tank reactor without any yield reduction from cell shearing. Hence, we showed the scalability and biotechnological exploitation of amoeba-based processes that can provide a reasonable alternative to chemical syntheses or extractions of phytochemicals from plant biomass.

Development of a multiparticle optical trajectography technique for hydrodynamic analysis of a stirred tank devoted to dark fermentation

Dark fermentation (DF) is a biological process able to produce hydrogen gas from organic waste which can play a key role as a building block in biorefineries. But the optimization of hydrodynamic conditions of DF is still needed to enhance gas-liquid mass transfer, thereby reducing the self-inhibitory effect of soluble hydrogen. Mass transfer enhancement is constrained, as hydromechanical stress on microorganisms must be limited and the economic sustainability of the process maintained.Recent results showed that DF is enhanced in the transition region between laminar and turbulent regimes. To gain a better knowledge of 3D hydrodynamic features in this regime, a modified optical trajectography technique was developed and applied to a 2-L bioreactor equipped with a dual-impeller device. The proposed methodology aims at monitoring the trajectories of up to ten particles as tracers at the same time using three cameras but is also able to provide the real-time position of the particles in the 2D-images of each camera to minimize the post-treatment time.The methodology, including stereoscopic camera calibration, real-time and post- treatment to reconstruct the 3D trajectories, was applied, and validated against 2D-PIV and CFD data. A good agreement was achieved, but regions neighboring wall and impeller were difficult to capture due to the particle size. The results highlighted that operating with five particles was able to reduce by a factor of 3–4 the measurement time in comparison to optical trajectography with a single particle as a tracer, while a higher number of tracers increased the occurrence of artifacts.

Volume change response and fabric evolution of granular MX80 bentonite along different hydro-mechanical stress paths

Despite the increasing understanding of bentonite behaviour, there is still missing evidence on how different hydro-mechanical loadings, including sequences of hydration and compression, affect the fabric and the volume change behaviour of the material. It is generally assumed that the interplay between the behaviour of clay assemblages and the overall fabric of the material is the reason of having final states that are dependent on the stress path followed. Here the results of an experimental campaign aiming to study these factors are reported and discussed. Free swelling and swelling pressure tests were performed, both followed by compression to a relatively high stress. The experimental program involved various samples that were dismantled at intermediate states in order to perform microstructural observations by means of mercury intrusion porosimetry and electronic scanning microscopy. It was observed that while the void ratio at a given stress level depends on the stress path, subsequent compression led to a unique virgin compression line. The data obtained at the microscale gave further insight for an interpretation of the volume change behaviour observed at the macroscale, showing that at high stress the material tends to recover the same fabric regardless of the path to saturation.

A coupled bio-chemo-hydro-mechanical model for bio-cementation in porous media

A key challenge involving microbially induced carbonate precipitation (MICP) is lack of rigorous yet practical theoretical models to predict the intricate biological–chemical–hydraulic–mechanical (BCHM) processes and the resulting bio-cement production. This paper presents a novel BCHM model based on multiphase, multispecies reactive transport approach in the framework of poroelasticity, aimed at achieving reasonable prediction of the produced bio-cement, and the enhanced geomechanical characteristics. The proposed model incorporates four key components: (i) coupling of hydro-mechanical stress–strain alterations with bio-chemical processes; (ii) stress–strain changes induced due to precipitation and growth of bio-cement within the porous matrix; (iii) spatiotemporal variability in hydraulic and stiffness characteristics of the treated medium; and (iv) velocity dependency of the attachment rate of bacteria. The fully coupled BCHM model predicts key unknown parameters during treatment including concentration of bacteria and chemical solutions, precipitated calcium carbonate, hydraulic properties of the solid skeleton, and in situ pore pressures and strains. The model was able to reasonably predict bio-cementation from two different laboratory column experiments. The Kozeny–Carman permeability equation is found to underestimate permeability reductions due to bio-cementation, while the Verma–Pruess relation could be more accurate. A sensitivity analysis revealed bio-cement distribution to be particularly sensitive to the attachment rate of bacteria.

Fault slip in hydraulic stimulation of geothermal reservoirs: Governing mechanisms and process-structure interaction

Hydraulic stimulation of geothermal reservoirs in low-permeability basement and crystalline igneous rock can enhance permeability by reactivation and shear dilation of existing fractures. The process is characterized by interaction between fluid flow, deformation, and the fractured structure of the formation. The flow is highly affected by the fracture network, which in turn is deformed because of hydromechanical stress changes caused by the fluid injection. This process-structure interaction is decisive for the outcome of hydraulic stimulation, and, in analysis of governing mechanisms, physics-based modeling has potential to complement field and experimental data. Here, we show how recently developed simulation technology is a valuable tool to understand governing mechanisms of hydromechanical coupled processes and the reactivation and deformation of faults. The methodology fully couples flow in faults and matrix with poroelastic matrix deformation and a contact mechanics model for the faults, including dilation because of slip. Key elements are high aspect ratios of faults and strong nonlinearities in highly coupled governing equations. Example simulations using our open-source software illustrate direct and indirect hydraulic fault reactivation and corresponding permeability enhancement. We investigate the effect of the fault and matrix permeability and the Biot coefficient. A higher matrix permeability leads to more leakage from a permeable fault and thus suppresses reactivation and slip of the fault compared to the case with a lower matrix permeability. If a fault is a barrier to flow, increase of pressure because of the fluid injection results in stabilization of the fault; the situation is opposite if the fault is highly permeable compared to the matrix. For the given setup, lowering the Biot coefficient results in more slip than the base case. While conceptually simple, the examples illustrate the strong hydromechanical couplings and the prospects of physics-based numerical models in investigating the dynamics.

CFD numerical simulation of particle suspension and hydromechanical stress in various designs of multi-stage bioleaching reactors

The performance of bioleaching stirred tank reactors (STR) is related to the homogeneity of biomass, substrates and dissolved gases. This work was focused on the characterization of the impeller design on bioreactor hydrodynamics and, more specifically on power, mixing efficiency and particle stress. Few studies addressed the issue of the impact of the impeller design on these, especially for multi-stage bioreactors which are the most commonly used at the industrial scale. To fill this lack, a two-stage solid-liquid computational fluid dynamics (CFD) model was simulated on more than 50 conditions to assess power consumption, dissipated power, suspension quality and particle stress. A dual impeller configuration was chosen using Rushton turbines, R600, Hydrofoil, Elephant Ear and HTPG impellers. Grinded pyrite-rich materials (average particles size: 80 μm) were considered as the solid phase at 3 different solid concentrations (10, 18 and 26% w/w). Considering the impeller power number (Np), the configuration with an axial impeller consumed less energy than a radial impeller in concordance with literature data. The results show that the impeller design had few to no effect on mixing efficiency considering a given power dissipation per unit volume. Independently on the impeller used, unique relationships were found between particle stress and mixing efficiency. This study gives new insights for reactor design and scaling of bioleaching stirred tank reactor and more specifically on the reduction of shear stress for the attached bacterial communities.

On the fate of sinking diatoms: the transport of active buoyancy-regulating cells in the ocean.

Diatoms are one of the most abundant, diverse and ecologically relevant phytoplanktonic group, contributing enormously to global biogeochemical processes like the carbon and silica cycles. This large success has been partly attributed to the mechanical and optical properties of the silica shell (the frustule) that envelops their body. But since they lack motility it is difficult to conceive how they cope with the fast-fluctuating environment they live in and where distributions of resources are very heterogeneous and dynamical. This pinpoints an important but yet poorly understood feature of diatoms physiology: buoyancy regulation that helps them controlling their sinking speed and position in the water column. While buoyancy regulation by light and nutrients availability has been well studied, the effect of hydromechanical stress via fluid shear has been rather overlooked when considering diatoms dynamics. Here, we aim to start filling this gap by first presenting direct experimental evidences for buoyancy control in response to hydro-mechanical stress and then review recent theoretical models where simple couplings between local shear and buoyancy control always result in heterogeneous cell distributions, specific accumulation regions within complex flows and increased sedimentation times to the depths, features of direct ecological relevance. We conclude by suggesting future experiments aiming to unveil such coupling and therefore gain better understanding on the fate of these fascinating microorganisms in their natural habitat. This article is part of the theme issue 'Stokes at 200 (part 2)'.

Hydromechanical Rock Slope Damage During Late Pleistocene and Holocene Glacial Cycles in an Alpine Valley

AbstractSubglacial water pressures influence groundwater conditions in proximal alpine valley rock slopes, varying with glacier advance and retreat in parallel with changing ice thickness. Fluctuating groundwater pressures in turn increase or reduce effective joint normal stresses, affecting the yield strength of discontinuities. Here we extend simplified assumptions of glacial debuttressing to investigate how glacier loading cycles together with changing groundwater pressures generate rock slope damage and prepare future slope instabilities. Using hydromechanical coupled numerical models closely based on the Aletsch Glacier valley in Switzerland, we simulate Late Pleistocene and Holocene glacier loading cycles including long‐term and annual groundwater fluctuations. Measurements of transient subglacial water pressures from ice boreholes in the Aletsch Glacier ablation area, as well as continuous monitoring of bedrock deformation from permanent Global Navigation Satellite Systems stations, help verify our model assumptions. While purely mechanical glacier loading cycles create only limited rock slope damage in our models, introducing a fluctuating groundwater table generates substantial new fracturing. Superposed annual groundwater cycles increase predicted damage. The cumulative effects are capable of destabilizing the eastern valley flank of our model in toppling‐mode failure, similar to field observations of active landslide geometry and kinematics. We find that hydromechanical fatigue is most effective acting in combination with long‐term loading and unloading of the slope during glacial cycles. Our results demonstrate that hydromechanical stresses associated with glacial cycles are capable of generating substantial rock slope damage and represent a key preparatory factor for paraglacial slope instabilities.

A thermodynamically consistent framework for visco-elasto-plastic creep and anisotropic damage in saturated frozen soils

This paper presents a poro-visco-elastic-plastic damageable model for saturated frozen soils within a rigorous theoretical framework. The effective fluid pressure, obtained considering the interfacial energy, is combined with the total Cauchy stress in order to formulate the hydro-mechanical effective stress applied to a soil skeleton. On the other hand, a two-stress variable constitutive relationship is adopted for saturated frozen soils to describe the essential features of frozen and unfrozen behaviour. Based on the continuum damage theory, the cross-anisotropic damage variables for saturated frozen soils are deduced. The proposed damage criterion and the new nonlinear damage surface for saturated frozen soils are all governed by the second invariants of the “double effective stress”, which combines the damaged effective stress with the effective hydro-mechanical stress. The validity of the visco-elasto-plastic model with no damage is verified by comparing its modelling results with experimental results obtained from uniaxial creep tests.

Elicitation-Based Method for Increasing the Production of Antioxidant and Bactericidal Phenolic Compounds in Dionaea muscipula J. Ellis Tissue.

The carnivorous plant Dionaea muscipula J. Ellis (Venus flytrap) is a widely known medical herb, capable of producing various phenolic compounds known for their strong antioxidant and antibacterial properties. In the pharmaceutical industry, Venus flytrap is grown in tissue cultures, as the natural population of D. muscipula is very limited. Here, we describe an improved method to increase the quantity and quality of phenolic compounds produced in D. muscipula. This is achieved by combining biotic elicitation (using Cronobacter sakazakii bacteria lysate) of D. muscipula cultured with rotary shaking (hydromechanical stress), which we describe here for the first time. The antibacterial activity and the antioxidant properties of the obtained compounds were studied on two antibiotic-resistant human pathogenic bacteria. The proposed plant culture conditions resulted in an increase in fresh weight, as well as a higher total phenolic content, in comparison to traditional tissue cultures on agar-solidified medium. With the use of high-performance liquid chromatography, we demonstrated that the described elicitation strategy leads to an increased synthesis of myricetin, caffeic acid, ellagic acid and plumbagin in D. muscipula tissue. We also found that a higher level of antioxidant activity, exhibited by the plant extract, corresponded with its higher phenylpropanoid content. The bactericidal activity of the extract against Staphylococcus aureus was dependent on the duration of plant culture under described elicitation conditions, whereas neither elicitation condition (duration or elicitor concentration) seemed relevant for the bactericidal activity of the extract towards Escherichia coli. This suggest that Gram-negative bacteria are less sensitive to compounds derived from Venus flytrap tissue.

Hydromechanical Behavior of Low-Swelling Soils Compacted at Low Water Content: Laboratory Study

Fine unsaturated soils are used in many applications, particularly in road infrastructure and in construction. These materials undergo deformations according to the stresses to which they are subjected. The purpose of this paper is to study the influence of hydromechanical stresses on the behavior of low swelling soils compacted at low water content in accordance with the French standard GTR 92 (Guide des Terrassements Routiers). Then, various experimental tests on an oedometer were carried out in the laboratory. Two types of low swelling soil sampled in Nasso on the outskirts of the town of Bobo Dioulasso (Burkina Faso) were used. After shuffling, each sample was moistened to its optimum water content and then compacted to 90% and 95% of its optimum density. Behavior tests show that these soils deform very little when subjected to hydromechanical stresses. However, these deformations are swelling in nature for low mechanical stresses and when the stresses are high, they tend to collapse. When these soils are subjected to a vertical stress of 420 kPa, the primary consolidation time is of the order of one minute for NH2 (a silty soil) and about ten minutes for NH3 (a silty-clayed soil).

Characterization of the local hydromechanical stress through experimental and numerical analysis of hydrodynamics under dark fermentation operating conditions

In mechanically stirred tanks, turbulent flow conditions have already been shown to impair biohydrogen production through dark fermentation even when the dimensionless Reynolds number (Re) is between 103 and 104. The aim was, therefore, to investigate the local hydrodynamic conditions encountered by bacterial aggregates in a fully baffled 2-L bioreactor equipped with a double stage Rusthton turbine in which dark fermentation had already been extensively studied. Both experimental and numerical tools (namely, Particle Image Velocimetry and Computational Fluid Dynamics) were applied to analyze the flow pattern and determine the main features of the turbulent flow. Experiments and simulations involved two levels of viscosity and three levels of agitation speed, corresponding to Re between 2.2·103 and 1.1·104 and power requirements P/V between 0.6 and 87 W/m3. A good agreement between simulated and experimental data was achieved, including velocity, turbulent kinetic energy and turbulent dissipation rate. Comparing the size of bacterial aggregates to Kolmogorov length scale, experimental and numerical results demonstrated that bacterial aggregates could be exposed to potentially damaging hydromechanical stress under turbulent flow in the vicinity of the impeller when Re = 2.2·103 and that this region rapidly expanded to the whole bioreactor when Re increased, which could explain the rapid fall of biohydrogen production vs.Re in the turbulent flow regime.

Optimization of the Impeller Design for Mesenchymal Stem Cell Culture on Microcarriers in Bioreactors

AbstractWhen agitating mesenchymal stem cells adhered on microcarriers in bioreactors, a compromise has to be found between sufficient particle suspension and limitation of hydromechanical stresses. The present study proposes a strategy to improve the design of an ‘elephant ear' impeller at the just‐suspended state by varying its relative size, blade slope angle, and position in the reactor. To do that, computational fluid dynamics simulations were coupled with multi‐objective optimization to minimize the hydromechanical stress encountered by the microcarriers. Two minimization criteria were considered: (P/V)@p and the energy dissipation function EDC. On the basis of 31 conditions, an optimal impeller geometry is proposed.

Dimensional analysis and CFD simulations of microcarrier ‘just-suspended’ state in mesenchymal stromal cells bioreactors

Large-scale mesenchymal stem/stromal cells culture uses 3D culture systems involving spherical solid particles, called microcarriers. Cells adhere on these spheres, which are then set in suspension in stirred tank bioreactors. This work was more particularly focused on the determination of the critical impeller agitation rate Njs, allowing complete beads suspension. It is indeed generally assumed that this value is a good compromise between sufficient nutrients homogenization, mass transfer and minimization of hydromechanical stress encountered by the cells. However, no robust correlation predicting Njs in the case of microcarriers can be found in literature. To fill this lack, a set of various operating conditions was carried out, dealing with geometrical variables and two different microcarriers, and Njs were experimentally determined for 140 conditions. An empirical correlation was established and a dimensional analysis was performed, showing that the impact of the particle concentration on Njs was function of the impeller design. Moreover, two dimensionless numbers characterizing the number of particle and an Archimede number applied on the particle cloud were found to better describe the impact of particle diameter and density on Njs. Simultaneously, a strategy based on Computational Fluid Dynamics simulations was conducted in order to predict Njs and was validated with the Njs experimental values.

The effect of clay water content in the Jet Erosion Test

The understanding of the onset of breaching induced by surface erosion is fundamental to enable definition of the level of protection afforded by embankments and provision of standards for the design of new structures and the upgrading of existing ones. Compacted embankment materials are generally partially saturated due to seasonal variation in the water content. At the onset of the overflow process embankments undergo to a wetting process due to the changes at the outer surface boundary conditions (i.e. overflow). Erosion behaviour is known to be a counterbalance between gravity forces and shear erosion forces. However, as the particle size decreases (i.e. clayey soils), gravitational forces become negligible and electrochemical interaction between particles play a dominant role. Clay microstructure (e.g. particle configuration and inter-particle forces) changes with the hydro-mechanical stresses history. Thus, it is necessary to consider the microstructural changes in particle configuration to understand the influence of microstructure on the macroscopic behaviour of clay during erosion. Upon wetting, clay have a swelling/collapse behaviour. This research presents experimental results on erosion of clay samples compacted at the same initial dry density but with different compaction water content. The influence of different wetting times on erosion is also investigated. We show that for a given as-compacted water content, the longer the wetting stage, and hence the higher the sample water content, the more erodible the samples. Additionally, for samples compacted at the same dry density, the ones compacted on the dry side of optimum are more erodible than samples compacted at the optimum water content, despite the lower water content at formation. We hypothesise that this may be due to the formation of a different initial microstructure in sample on the dry side of optimum (i.e. bi-modal pore size distribution). Our results contribute to the fundamental understanding of time-dependent mechanisms that influence erosion of clay embankments during overflow and, hence, to embankment failure. In addition, these tests show how basic concepts of unsaturated soil mechanics can serve as a guide to ‘design’ the compaction conditions of embankment material.

Influence of Impeller Geometry on Hydromechanical Stress in Stirred Liquid/Liquid Dispersions

Hydromechanical stress is a crucial parameter for a broad range of multiphase processes in the field of (bio)chemical engineering. The effect of impeller type and geometry on hydromechanical stress in stirred tanks is important. The present study aims at characterizing conventional and new impeller types in terms of particle stress. A two-phase liquid/liquid noncoalescing dispersion system is employed, and the drop breakage is monitored in-line in a stirred tank. The published effects of agitation on drop deformation are confirmed and expanded significantly for five modified new impeller types. Radial impellers are advantageous for applications where low shear conditions are desired. A modified propeller with a peripheral ring and the developed wave-ribbon impellers present remarkable results by producing significantly low and high hydromechanical stress, respectively. The results obtained are correlated in terms of mean and maximum energy dissipation rate, as well as circulation frequency in the impeller...

Characterizing the fluid dynamics in the flow fields of cylindrical orbitally shaken bioreactors with different geometry sizes.

Orbitally shaken bioreactors (OSRs) are commonly used for the cultivation of mammalian cells in suspension. To aid the geometry designing and optimizing of OSRs, we conducted a three-dimensional computational fluid dynamics (CFD) simulation to characterize the flow fields in a 10 L cylindrical OSR with different vessel diameters. The liquid wave shape captured by a camera experimentally validated the CFD models established for the cylindrical OSR. The geometry size effect on volumetric mass transfer coefficient (kLa) and hydromechanical stress was analyzed by varying the ratio of vessel diameter (d) to liquid height at static (h L), d/h L. The highest value of kLa about 30 h-1 was observed in the cylindrical vessel with the d/h L of 6.35. Moreover, the magnitudes of shear stress and energy dissipation rate in all the vessels tested were below their minimum values causing cells damage separately, which indicated that the hydromechanical-stress environment in OSRs is suitable for cells cultivation in suspension. Finally, the CFD results suggested that the d/h L higher than 8.80 should not be adopted for the 10 L cylindrical OSR at the shaking speed of 180 rpm because the "out of phase" state probably will happen there.