A systematic methodology for formulating,implementing,solving and verifying discrete adjoint of the compressible Reynolds-averaged Navier-Stokes（RANS） equations for aerodynamic design optimization on unstructured me...A systematic methodology for formulating,implementing,solving and verifying discrete adjoint of the compressible Reynolds-averaged Navier-Stokes（RANS） equations for aerodynamic design optimization on unstructured meshes is proposed.First,a general adjoint formulation is constructed for the entire optimization problem,including parameterization,mesh deformation,flow solution and computation of the objective function,which is followed by detailed formulations of matrix-vector products arising in the adjoint model.According to this formulation,procedural components of implementing the required matrix-vector products are generated by means of automatic differentiation（AD） in a structured and modular manner.Furthermore,a duality-preserving iterative algorithm is employed to solve flow adjoint equations arising in the adjoint model,ensuring identical convergence rates for the tangent and the adjoint models.A three-step strategy is adopted to verify the adjoint computation.The proposed method has several remarkable features：the use of AD techniques avoids tedious and error-prone manual derivation and programming;duality is strictly preserved so that consistent and highly accurate discrete sensitivities can be obtained;and comparable efficiency to hand-coded implementation can be achieved.Upon the current discrete adjoint method,a gradient-based optimization framework has been developed and applied to a drag reduction problem.展开更多
Soil arsenic(As)pollution from mining and industrial sources is a serious issue in China.Earthworms are considered ecosystem engineers and contribute to soil fertility development and maintenance of soil physico-chemi...Soil arsenic(As)pollution from mining and industrial sources is a serious issue in China.Earthworms are considered ecosystem engineers and contribute to soil fertility development and maintenance of soil physico-chemical properties.In this study,earthworms were exposed to soils with different sodium arsenite concentrations(0,5,20,and 80 mg As kg^(-1))for 60 d to investigate the changes in soil properties and the responses of the earthworms(e.g.,burrowing activity and respiration).Earthworm burrowing activity decreased with increasing arsenite concentrations,and earthworm respiration was significantly lower in soils with 20 and 80 mg As kg^(-1) compared to 0 mg As kg^(-1).Changes in soil properties were also observed after incubation of As-amended soil with earthworms.Specifically,soil pH decreased,while soil electrical conductivity and contents of soil NH3--N,Olsen-P,and available K increased.Our results suggest that arsenite negatively impacts the metabolic activity of earthworms,leading to reduced burrowing activity,which in turn modifies the effects of earthworms on soil fertility and remediation.展开更多
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘A systematic methodology for formulating,implementing,solving and verifying discrete adjoint of the compressible Reynolds-averaged Navier-Stokes（RANS） equations for aerodynamic design optimization on unstructured meshes is proposed.First,a general adjoint formulation is constructed for the entire optimization problem,including parameterization,mesh deformation,flow solution and computation of the objective function,which is followed by detailed formulations of matrix-vector products arising in the adjoint model.According to this formulation,procedural components of implementing the required matrix-vector products are generated by means of automatic differentiation（AD） in a structured and modular manner.Furthermore,a duality-preserving iterative algorithm is employed to solve flow adjoint equations arising in the adjoint model,ensuring identical convergence rates for the tangent and the adjoint models.A three-step strategy is adopted to verify the adjoint computation.The proposed method has several remarkable features：the use of AD techniques avoids tedious and error-prone manual derivation and programming;duality is strictly preserved so that consistent and highly accurate discrete sensitivities can be obtained;and comparable efficiency to hand-coded implementation can be achieved.Upon the current discrete adjoint method,a gradient-based optimization framework has been developed and applied to a drag reduction problem.
基金This study was financed by the National Key R&D Program of China(No.2017Y FD 0501405)the National Natural Science Foundation of China(No.41471203)+1 种基金the Natural Science Projects of Henan University of Technology,China(No.2019BS037)the Key Projects of Shanghai Municipal Agricultural Commission,China(No.20166-3-2).
文摘Soil arsenic(As)pollution from mining and industrial sources is a serious issue in China.Earthworms are considered ecosystem engineers and contribute to soil fertility development and maintenance of soil physico-chemical properties.In this study,earthworms were exposed to soils with different sodium arsenite concentrations(0,5,20,and 80 mg As kg^(-1))for 60 d to investigate the changes in soil properties and the responses of the earthworms(e.g.,burrowing activity and respiration).Earthworm burrowing activity decreased with increasing arsenite concentrations,and earthworm respiration was significantly lower in soils with 20 and 80 mg As kg^(-1) compared to 0 mg As kg^(-1).Changes in soil properties were also observed after incubation of As-amended soil with earthworms.Specifically,soil pH decreased,while soil electrical conductivity and contents of soil NH3--N,Olsen-P,and available K increased.Our results suggest that arsenite negatively impacts the metabolic activity of earthworms,leading to reduced burrowing activity,which in turn modifies the effects of earthworms on soil fertility and remediation.
