Lynn B. Reid

A porosity-gradient replacement approach for computational simulation of chemical-dissolution front propagation in fluid-saturated porous media including pore-fluid compressibility

In dealing with chemical-dissolution-front propagation problems in fluid-saturated porous media, the chemical dissolution front represented by the porosity of the medium may have a very steep slope (i.e., a very large porosity gradient) at the dissolution front, depending on the mineral dissolution ratio that is defined as the equilibrium concentration of the dissolved minerals in the pore-fluid to the solid molar density of the dissolvable minerals in the solid matrix. When the mineral dissolution ratio approaches zero, the theoretical value of the porosity gradient tends to infinity at the chemical dissolution front. Even for a very small value of the mineral dissolution ratio, which is very common in geochemical systems, the porosity gradient can be large enough to cause the solution hard to converge when the conventional finite element method is used to solve a chemical dissolution problem in a fluid-saturated porous medium where the pore-fluid is compressible. To improve the convergent speed of solution, a porosity-gradient replacement approach, in which the term involving porosity-gradient computation is replaced by a new term consisting of pore-fluid density-gradient and pressure-gradient computation, is first proposed and then incorporated into the finite element method in this study. Through comparing the numerical results obtained from the proposed approach with the theoretical solutions for a benchmark problem, it has been demonstrated that not only can the solution divergence be avoid, but also the accurate simulation results can be obtained when the proposed porosity-gradient replacement approach is used to solve chemical-dissolution-front propagation problems in fluid-saturated porous media including pore-fluid compressibility.

The potential for convection and implications for geothermal energy in the Perth Basin, Western Australia

Convection of groundwater in aquifers can create areas of anomalously high temperature at shallow depths which could be exploited for geothermal energy. Temperature measurements in the Perth Basin (Western Australia) reveal thermal patterns that are consistent with convection in the Yarragadee Aquifer. This observation is supported by Rayleigh number calculations, which show that convection is possible within the range of aquifer thickness, geothermal gradient, salinity gradient and permeability encountered in the Yarragadee Aquifer, assuming that the aquifer can be treated as a homogeneous anisotropic layer. Numerical simulations of convection in a simplified model of the Yarragadee Aquifer show that: (1) the spacing of convective upwellings can be predicted from aquifer thickness and permeability anisotropy; (2) convective upwellings may be circular or elongate in plan view; (3) convective upwellings create significant temperature enhancements relative to the conductive profile; (4) convective flow rates are similar to regional groundwater flow rates; and (5) convection homogenises salinity within the aquifer. Further work is required to constrain the average horizontal and vertical permeability of the Yarragadee Aquifer, to assess the validity of treating the aquifer as a homogeneous anisotropic layer, and to determine the impact of realistic aquifer geometry and advection on convection.RésuméLa convection des eaux souterraines dans les aquifères peut créer des zones de températures anormalement élevées à faible profondeur qui pourraient être exploitées pour l’énergie géothermique. Les mesures de température dans le bassin de Perth (Australie occidentale) révèlent des caractéristiques thermales cohérentes avec une convection dans l’aquifère de Yarragadee. Cette observation est étayée par des calculs du nombre de Rayleigh, qui montrent que la convection est possible pour l’ordre de grandeur d’épaisseur de l’aquifère, le gradient géothermal, le gradient de salinité, et la perméabilité rencontrées dans l’aquifère de Yarragadee, en supposant que l’aquifère puisse être traité comme une couche homogène et anisotrope. Des simulations numériques de la convection dans un modèle simplifié de l’aquifère de Yarragadee montrent que : (1) l’espacement des flux convectifs ascendants peut être prédit d’après l’épaisseur de l’aquifère et l’anisotropie de la perméabilité; (2) les flux convectifs ascendants peuvent être circulaires ou allongés dans une vue en plan ; (3) les flux convectifs ascendants créent des accroissements de température significatifs par rapport au profil du conduit ; (4) les débits des flux convectifs sont similaires aux débits des écoulements régionaux des eaux souterraines; et (5) la convection homogénéise la salinité dans l’aquifère. D’autres travaux sont nécessaires pour tenir compte de la perméabilité moyenne horizontale et verticale de l’aquifère de Yarragadee, pour juger de la validité d’un traitement de l’aquifère comme couche homogène anisotrope, et pour déterminer l’impact d’une géométrie réaliste de l’aquifère et de l’advection sur la convection.ResumenLa convección del agua subterránea en acuíferos puede crear áreas de temperaturas anómalamente altas en profundidades someras que podrían ser explotadas para energía geotérmica. Las medidas de temperatura en la cuenca de Perth (Australia Occidental) revelaron esquemas termales que son consistentes con la convección en el acuífero Yarragadee. Esta observación está apoyada por cálculos del número de Rayleigh, que muestra que la convección es posible dentro del rango de los espesores del acuífero, gradiente geotérmico, gradiente de salinidad y permeabilidad encontradas en el acuífero Yarragadee, suponiendo que el acuífero puede ser tratado como una capa homogénea anisotrópica. Las simulaciones numéricas de convección en un modelo simplificado del acuífero Yarragadee muestra que: (1) El espaciado de surgencias convectivas puede ser predicho a partir del espesor del acuífero y de la anisotropía de la permeabilidad; (2) Las surgencias convectivas pueden ser circulares o alongados en vista en planta; (3) Las surgencias convectivas crean un acrecentamiento significativo de la temperatura en relación al perfil conductivo; (4) Los ritmos de flujos convectivos son similares a los ritmos de flujo regional del agua subterránea; y (5) La convección homogeiniza la salinidad dentro del acuífero. Se requiere trabajo adicional para restringir la permeabilidad promedio vertical y horizontal del acuífero Yarragadee, para evaluar la validez de tratar al acuífero como una capa anisotrópica homogénea y determinar el impacto de la geometría realística del acuífero y de la advección sobre la convección.摘要含水层中地下水的对流可在浅部造成局部高温异常,并用于开采地热能。澳大利亚西部珀斯盆地的测温量热揭示出与Yarragadee含水层对流相一致的热模式。雷利数的计算支持这一观测结果,并表明在Yarragadee含水层中对流发生在一定含水层厚度、地温梯度、盐分梯度以及渗透系数范围内,假定含水层为均质各向异性的。对Yarragadee含水层简化模型的对流数值模拟表明:(1)对流上涌的间距可通过含水层厚度及渗透性各向异性预测;(2)在平面上对流上涌是可循环或拉长的;(3)相对于传导剖面对流上涌可产生更大的温度增强;(4)对流速度与区域上的地下水流速相似;(5)对流使得含水层盐分均一化。进一步工作需要限制Yarragadee含水层的水平和垂直平均渗透系数,用于评价视含水层为均质各向异性的有效性,确定真实含水层尺度及对流中平流的影响。ResumoA conveção em aquíferos pode criar áreas anormais de alta temperatura a profundidades baixas, as quais podem ser exploradas para energia geotérmica. Medições de temperatura na Bacia de Perth (Austrália Ocidental) mostram padrões térmicos consistentes com conveção no Aquífero Yarragadee. Esta observação é apoiada pelos cálculos do número de Rayleigh, os quais mostram que a conveção é possível dentro da gama de espessuras, gradientes geotérmicos, gradientes de salinidade e permeabilidades encontradas no Aquífero Yarragadee, assumindo que o aquífero pode ser tratado como uma camada anisotrópica homogénea. Um modelo simplificado de simulações numéricas de conveção do Aquífero Yarragadee mostra que: (1) O espaçamento de upwellings convetivos pode ser previsto a partir da espessura do aquífero e da anisotropia da permeabilidade, (2) Upwellings convetivos podem ser circulares ou alongados no plano horizontal, (3) Upwellings convetivos criam condições significativamente melhores na temperatura em relação ao perfil condutivo, (4) As taxas de fluxo convetivas são similares às taxas de fluxo regional da água subterrânea, e (5) A conveção homogeneiza a salinidade dentro do aquífero. Torna-se necessário realizar algum trabalho adicional para restringir os parâmetros da permeabilidade média horizontal e vertical do Aquífero Yarragadee, para avaliar a validade de considerar o aquífero como uma camada anisotrópica homogénea, e para determinar o impacte da geometria real do aquífero e da adveção na conveção.

Evolution of FLASH, a multi-physics scientific simulation code for high-performance computing

The FLASH code has evolved into a modular and extensible scientific simulation software system over the decade of its existence. During this time it has been cumulatively used by over a thousand researchers to investigate problems in astrophysics, cosmology, and in some areas of basic physics, such as turbulence. Recently, many new capabilities have been added to the code to enable it to simulate problems in high-energy density physics. Enhancements to these capabilities continue, along with enhancements enabling simulations of problems in fluid-structure interactions. The code started its life as an amalgamation of already existing software packages and sections of codes developed independently by various participating members of the team for other purposes. The code has evolved through a mixture of incremental and deep infrastructural changes. In the process, it has undergone four major revisions, three of which involved a significant architectural advancement. Along the way, a software process evolved that addresses the issues of code verification, maintainability, and support for the expanding user base. The software process also resolves the conflicts arising out of being in development and production simultaneously with multiple research projects, and between performance and portability. This paper describes the process of code evolution with emphasis on the design decisions and software management policies that have been instrumental in the success of the code. The paper also makes the case for a symbiotic relationship between scientific research and good software engineering of the simulation software.

Shallow geothermal regime in the Perth Metropolitan Area

Exploration of Perths geothermal potential has been performed by the Western Australian Geothermal Centre of Excellence (WAGCoE). Detailed vertical temperature and gamma ray logging of 17 Western Australia Department of Waters (DoW) Artesian Monitoring (AM) wells was completed throughout the Perth Metropolitan Area (PMA). In addition, temperature logs from 53 DoW AM wells measured in the 1980s were digitised into LAS format. The logged data are available in the WAGCoE Data Catalogue. Analysis of the gamma ray logs yielded the first estimates of radiogenic heat production in Perth Basin formations. Values by formation ranged between 0.24 and 1.065 μW m−3. The temperature logs provide a picture of true formation temperatures within shallow sediments in the Perth Basin. A three-dimensional model of the temperature distribution was used to produce maps of temperature at depth and on the top of the Yarragadee aquifer. The temperature data were interpreted with a one-dimensional conductive heat model. Significant differences between the model and the observations was indicative of heat moving via non-conductive mechanisms, such as advection or convection. Evidence of non-conductive or advective heat flow is demonstrated in most formations in the region, with significant effects in the aquifers. Average conductive geothermal gradients range from 13°C km−1 to 39°C km−1, with sandstone formations exhibiting average gradients of approximately 25°C km−1, while insulating silt/shale formations show higher average gradients of over 30°C km−1. To produce preliminary heat flow estimates, temperature gradients were combined with thermal conductivities measured elsewhere. The geometric mean heat flow estimates range between 64 mW m−2 to 91 mW m−2, with the standard deviation of the arithmetic mean heat flow ranging between 15 and 23 mW m−2. The study characterises the shallow temperature regime in the Perth Metropolitan Area, which is of direct relevance towards developing commercial geothermal projects.

Ongoing verification of a multiphysics community code: FLASH

When developing a complex, multi‐authored code, daily testing on multiple platforms and under a variety of conditions is essential. It is therefore necessary to have a regression test suite that is easily administered and configured, as well as a way to easily view and interpret the test suite results. We describe the methodology for verification of FLASH, a highly capable multiphysics scientific application code with a wide user base. The methodology uses a combination of unit and regression tests and an in‐house testing software that is optimized for operation under limited resources. Although our practical implementations do not always comply with theoretical regression‐testing research, our methodology provides a comprehensive verification of a large scientific code under resource constraints.Copyright

Pragmatic optimizations for better scientific utilization of large supercomputers

Advances in modeling and algorithms, combined with growth in computing resources, have enabled simulations of multiphysics–multiscale phenomena that can greatly enhance our scientific understanding. However, on currently available high-performance computing (HPC) resources, maximizing the scientific outcome of simulations requires many trade-offs. In this paper we describe our experiences in running simulations of the explosion phase of Type Ia supernovae on the largest available platforms. The simulations use FLASH, a modular, adaptive mesh, parallel simulation code with a wide user base. The simulations use multiple physics components: hydrodynamics, gravity, a sub-grid flame model, a three-stage burning model, and a degenerate equation of state. They also use Lagrangian tracer particles, which are then post-processed to determine the nucleosynthetic yields. We describe the simulation planning process, and the algorithmic optimizations and trade-offs that were found to be necessary. Several of the optimizations and trade-offs were made during the course of the simulations as our understanding of the challenges evolved, or when simulations went into previously unexplored physical regimes. We also briefly outline the anticipated challenges of, and our preparations for, the next-generation computing platforms.

The software development process of FLASH, a multiphysics simulation code

The FLASH code has evolved into a modular and extensible scientific simulation software system over the decade of its existence. During this time it has been cumulatively used by over a thousand researchers in several scientific communities (i.e. astrophysics, cosmology, high-energy density physics, turbulence, fluid-structure interactions) to obtain results for research. The code started its life as an amalgamation of two already existing software packages and sections of other codes developed independently by various participating members of the team for other purposes. In the evolution process it has undergone four major revisions, three of which involved a significant architectural advancement. A corresponding evolution of the software process and policies for maintenance occurred simultaneously. The code is currently in its 4.x release with a substantial user community. Recently there has been an upsurge in the contributions by external users; some provide significant new capability. This paper outlines the software development and evolution processes that have contributed to the success of the FLASH code.

Experiences using smaash to manage data-intensive simulations

High performance scientific computer simulations created with such systems as the University of Chicagos FLASH code generate enormous amounts of data that must be captured, cataloged, and analyzed. Unless this is formally done, monitoring such simulations, tracking and reproducing old ones, and analyzing and archiving their output, can be haphazard and idiosyncratic. Smaash, a simulation management and analysis system that has been developed at the University of Chicago and Argonne National Laboratory, seeks to solve some of these problems by offering what approaches a single point of control and analysis, a metadata-base, and a set of tools that automate some of what scientists have been doing by hand. Smaash was designed to be independent of the particular simulation code, and is accessible from many computing platforms. It is automatic and standardized, and was built using open source software tools. Data security is considered throughout the process, yet users are insulated from onerous verification procedures. Because the system was developed with feedback from scientific users, its user interface reflects how scientists work in their daily life. We describe our system and a typical simulation it was designed to support. We illustrate its utility with several examples describing our experience of freeing scientists from the data manipulation phase to focus on the computational results and the analysis of high performance computing.

The potential for convection and implications for geothermal energy in the Perth Basin, Western Australia | Le potentiel de convection et ses implications pour l'énergie géothermique dans le bassin de Perth, Australie occidentale

Convection of groundwater in aquifers can create areas of anomalously high temperature at shallow depths which could be exploited for geothermal energy. Temperature measurements in the Perth Basin (Western Australia) reveal thermal patterns that are consistent with convection in the Yarragadee Aquifer. This observation is supported by Rayleigh number calculations, which show that convection is possible within the range of aquifer thickness, geothermal gradient, salinity gradient and permeability encountered in the Yarragadee Aquifer, assuming that the aquifer can be treated as a homogeneous anisotropic layer. Numerical simulations of convection in a simplified model of the Yarragadee Aquifer show that: (1) the spacing of convective upwellings can be predicted from aquifer thickness and permeability anisotropy; (2) convective upwellings may be circular or elongate in plan view; (3) convective upwellings create significant temperature enhancements relative to the conductive profile; (4) convective flow rates are similar to regional groundwater flow rates; and (5) convection homogenises salinity within the aquifer. Further work is required to constrain the average horizontal and vertical permeability of the Yarragadee Aquifer, to assess the validity of treating the aquifer as a homogeneous anisotropic layer, and to determine the impact of realistic aquifer geometry and advection on convection.RésuméLa convection des eaux souterraines dans les aquifères peut créer des zones de températures anormalement élevées à faible profondeur qui pourraient être exploitées pour l’énergie géothermique. Les mesures de température dans le bassin de Perth (Australie occidentale) révèlent des caractéristiques thermales cohérentes avec une convection dans l’aquifère de Yarragadee. Cette observation est étayée par des calculs du nombre de Rayleigh, qui montrent que la convection est possible pour l’ordre de grandeur d’épaisseur de l’aquifère, le gradient géothermal, le gradient de salinité, et la perméabilité rencontrées dans l’aquifère de Yarragadee, en supposant que l’aquifère puisse être traité comme une couche homogène et anisotrope. Des simulations numériques de la convection dans un modèle simplifié de l’aquifère de Yarragadee montrent que : (1) l’espacement des flux convectifs ascendants peut être prédit d’après l’épaisseur de l’aquifère et l’anisotropie de la perméabilité; (2) les flux convectifs ascendants peuvent être circulaires ou allongés dans une vue en plan ; (3) les flux convectifs ascendants créent des accroissements de température significatifs par rapport au profil du conduit ; (4) les débits des flux convectifs sont similaires aux débits des écoulements régionaux des eaux souterraines; et (5) la convection homogénéise la salinité dans l’aquifère. D’autres travaux sont nécessaires pour tenir compte de la perméabilité moyenne horizontale et verticale de l’aquifère de Yarragadee, pour juger de la validité d’un traitement de l’aquifère comme couche homogène anisotrope, et pour déterminer l’impact d’une géométrie réaliste de l’aquifère et de l’advection sur la convection.ResumenLa convección del agua subterránea en acuíferos puede crear áreas de temperaturas anómalamente altas en profundidades someras que podrían ser explotadas para energía geotérmica. Las medidas de temperatura en la cuenca de Perth (Australia Occidental) revelaron esquemas termales que son consistentes con la convección en el acuífero Yarragadee. Esta observación está apoyada por cálculos del número de Rayleigh, que muestra que la convección es posible dentro del rango de los espesores del acuífero, gradiente geotérmico, gradiente de salinidad y permeabilidad encontradas en el acuífero Yarragadee, suponiendo que el acuífero puede ser tratado como una capa homogénea anisotrópica. Las simulaciones numéricas de convección en un modelo simplificado del acuífero Yarragadee muestra que: (1) El espaciado de surgencias convectivas puede ser predicho a partir del espesor del acuífero y de la anisotropía de la permeabilidad; (2) Las surgencias convectivas pueden ser circulares o alongados en vista en planta; (3) Las surgencias convectivas crean un acrecentamiento significativo de la temperatura en relación al perfil conductivo; (4) Los ritmos de flujos convectivos son similares a los ritmos de flujo regional del agua subterránea; y (5) La convección homogeiniza la salinidad dentro del acuífero. Se requiere trabajo adicional para restringir la permeabilidad promedio vertical y horizontal del acuífero Yarragadee, para evaluar la validez de tratar al acuífero como una capa anisotrópica homogénea y determinar el impacto de la geometría realística del acuífero y de la advección sobre la convección.摘要含水层中地下水的对流可在浅部造成局部高温异常,并用于开采地热能。澳大利亚西部珀斯盆地的测温量热揭示出与Yarragadee含水层对流相一致的热模式。雷利数的计算支持这一观测结果,并表明在Yarragadee含水层中对流发生在一定含水层厚度、地温梯度、盐分梯度以及渗透系数范围内,假定含水层为均质各向异性的。对Yarragadee含水层简化模型的对流数值模拟表明:(1)对流上涌的间距可通过含水层厚度及渗透性各向异性预测;(2)在平面上对流上涌是可循环或拉长的;(3)相对于传导剖面对流上涌可产生更大的温度增强;(4)对流速度与区域上的地下水流速相似;(5)对流使得含水层盐分均一化。进一步工作需要限制Yarragadee含水层的水平和垂直平均渗透系数,用于评价视含水层为均质各向异性的有效性,确定真实含水层尺度及对流中平流的影响。ResumoA conveção em aquíferos pode criar áreas anormais de alta temperatura a profundidades baixas, as quais podem ser exploradas para energia geotérmica. Medições de temperatura na Bacia de Perth (Austrália Ocidental) mostram padrões térmicos consistentes com conveção no Aquífero Yarragadee. Esta observação é apoiada pelos cálculos do número de Rayleigh, os quais mostram que a conveção é possível dentro da gama de espessuras, gradientes geotérmicos, gradientes de salinidade e permeabilidades encontradas no Aquífero Yarragadee, assumindo que o aquífero pode ser tratado como uma camada anisotrópica homogénea. Um modelo simplificado de simulações numéricas de conveção do Aquífero Yarragadee mostra que: (1) O espaçamento de upwellings convetivos pode ser previsto a partir da espessura do aquífero e da anisotropia da permeabilidade, (2) Upwellings convetivos podem ser circulares ou alongados no plano horizontal, (3) Upwellings convetivos criam condições significativamente melhores na temperatura em relação ao perfil condutivo, (4) As taxas de fluxo convetivas são similares às taxas de fluxo regional da água subterrânea, e (5) A conveção homogeneiza a salinidade dentro do aquífero. Torna-se necessário realizar algum trabalho adicional para restringir os parâmetros da permeabilidade média horizontal e vertical do Aquífero Yarragadee, para avaliar a validade de considerar o aquífero como uma camada anisotrópica homogénea, e para determinar o impacte da geometria real do aquífero e da adveção na conveção.

The potential for convection and implications for geothermal energy in the Perth Basin, Western Australia@@@Le potentiel de convection et ses implications pour l’énergie géothermique dans le bassin de Perth, Australie occidentale@@@El potencial de convección y las implicancias para la energía geotérmica en la Cuenca de Perth, Australia Occidental@@@澳大利亚西部珀斯盆地地下水对流的潜力及其地热能意义@@@O potencial para conveção e implicações para a energia geotérmica na Bacia de Perth, Austrália Ocidental

Convection of groundwater in aquifers can create areas of anomalously high temperature at shallow depths which could be exploited for geothermal energy. Temperature measurements in the Perth Basin (Western Australia) reveal thermal patterns that are consistent with convection in the Yarragadee Aquifer. This observation is supported by Rayleigh number calculations, which show that convection is possible within the range of aquifer thickness, geothermal gradient, salinity gradient and permeability encountered in the Yarragadee Aquifer, assuming that the aquifer can be treated as a homogeneous anisotropic layer. Numerical simulations of convection in a simplified model of the Yarragadee Aquifer show that: (1) the spacing of convective upwellings can be predicted from aquifer thickness and permeability anisotropy; (2) convective upwellings may be circular or elongate in plan view; (3) convective upwellings create significant temperature enhancements relative to the conductive profile; (4) convective flow rates are similar to regional groundwater flow rates; and (5) convection homogenises salinity within the aquifer. Further work is required to constrain the average horizontal and vertical permeability of the Yarragadee Aquifer, to assess the validity of treating the aquifer as a homogeneous anisotropic layer, and to determine the impact of realistic aquifer geometry and advection on convection.RésuméLa convection des eaux souterraines dans les aquifères peut créer des zones de températures anormalement élevées à faible profondeur qui pourraient être exploitées pour l’énergie géothermique. Les mesures de température dans le bassin de Perth (Australie occidentale) révèlent des caractéristiques thermales cohérentes avec une convection dans l’aquifère de Yarragadee. Cette observation est étayée par des calculs du nombre de Rayleigh, qui montrent que la convection est possible pour l’ordre de grandeur d’épaisseur de l’aquifère, le gradient géothermal, le gradient de salinité, et la perméabilité rencontrées dans l’aquifère de Yarragadee, en supposant que l’aquifère puisse être traité comme une couche homogène et anisotrope. Des simulations numériques de la convection dans un modèle simplifié de l’aquifère de Yarragadee montrent que : (1) l’espacement des flux convectifs ascendants peut être prédit d’après l’épaisseur de l’aquifère et l’anisotropie de la perméabilité; (2) les flux convectifs ascendants peuvent être circulaires ou allongés dans une vue en plan ; (3) les flux convectifs ascendants créent des accroissements de température significatifs par rapport au profil du conduit ; (4) les débits des flux convectifs sont similaires aux débits des écoulements régionaux des eaux souterraines; et (5) la convection homogénéise la salinité dans l’aquifère. D’autres travaux sont nécessaires pour tenir compte de la perméabilité moyenne horizontale et verticale de l’aquifère de Yarragadee, pour juger de la validité d’un traitement de l’aquifère comme couche homogène anisotrope, et pour déterminer l’impact d’une géométrie réaliste de l’aquifère et de l’advection sur la convection.ResumenLa convección del agua subterránea en acuíferos puede crear áreas de temperaturas anómalamente altas en profundidades someras que podrían ser explotadas para energía geotérmica. Las medidas de temperatura en la cuenca de Perth (Australia Occidental) revelaron esquemas termales que son consistentes con la convección en el acuífero Yarragadee. Esta observación está apoyada por cálculos del número de Rayleigh, que muestra que la convección es posible dentro del rango de los espesores del acuífero, gradiente geotérmico, gradiente de salinidad y permeabilidad encontradas en el acuífero Yarragadee, suponiendo que el acuífero puede ser tratado como una capa homogénea anisotrópica. Las simulaciones numéricas de convección en un modelo simplificado del acuífero Yarragadee muestra que: (1) El espaciado de surgencias convectivas puede ser predicho a partir del espesor del acuífero y de la anisotropía de la permeabilidad; (2) Las surgencias convectivas pueden ser circulares o alongados en vista en planta; (3) Las surgencias convectivas crean un acrecentamiento significativo de la temperatura en relación al perfil conductivo; (4) Los ritmos de flujos convectivos son similares a los ritmos de flujo regional del agua subterránea; y (5) La convección homogeiniza la salinidad dentro del acuífero. Se requiere trabajo adicional para restringir la permeabilidad promedio vertical y horizontal del acuífero Yarragadee, para evaluar la validez de tratar al acuífero como una capa anisotrópica homogénea y determinar el impacto de la geometría realística del acuífero y de la advección sobre la convección.摘要含水层中地下水的对流可在浅部造成局部高温异常,并用于开采地热能。澳大利亚西部珀斯盆地的测温量热揭示出与Yarragadee含水层对流相一致的热模式。雷利数的计算支持这一观测结果,并表明在Yarragadee含水层中对流发生在一定含水层厚度、地温梯度、盐分梯度以及渗透系数范围内,假定含水层为均质各向异性的。对Yarragadee含水层简化模型的对流数值模拟表明:(1)对流上涌的间距可通过含水层厚度及渗透性各向异性预测;(2)在平面上对流上涌是可循环或拉长的;(3)相对于传导剖面对流上涌可产生更大的温度增强;(4)对流速度与区域上的地下水流速相似;(5)对流使得含水层盐分均一化。进一步工作需要限制Yarragadee含水层的水平和垂直平均渗透系数,用于评价视含水层为均质各向异性的有效性,确定真实含水层尺度及对流中平流的影响。ResumoA conveção em aquíferos pode criar áreas anormais de alta temperatura a profundidades baixas, as quais podem ser exploradas para energia geotérmica. Medições de temperatura na Bacia de Perth (Austrália Ocidental) mostram padrões térmicos consistentes com conveção no Aquífero Yarragadee. Esta observação é apoiada pelos cálculos do número de Rayleigh, os quais mostram que a conveção é possível dentro da gama de espessuras, gradientes geotérmicos, gradientes de salinidade e permeabilidades encontradas no Aquífero Yarragadee, assumindo que o aquífero pode ser tratado como uma camada anisotrópica homogénea. Um modelo simplificado de simulações numéricas de conveção do Aquífero Yarragadee mostra que: (1) O espaçamento de upwellings convetivos pode ser previsto a partir da espessura do aquífero e da anisotropia da permeabilidade, (2) Upwellings convetivos podem ser circulares ou alongados no plano horizontal, (3) Upwellings convetivos criam condições significativamente melhores na temperatura em relação ao perfil condutivo, (4) As taxas de fluxo convetivas são similares às taxas de fluxo regional da água subterrânea, e (5) A conveção homogeneiza a salinidade dentro do aquífero. Torna-se necessário realizar algum trabalho adicional para restringir os parâmetros da permeabilidade média horizontal e vertical do Aquífero Yarragadee, para avaliar a validade de considerar o aquífero como uma camada anisotrópica homogénea, e para determinar o impacte da geometria real do aquífero e da adveção na conveção.