摘要:

AbstractThis paper presents an advanced method for a 2‐dimensional analysis of transient natural convection by finite element method. The present method, based on stream function—vorticity formulation, could get rid of numerical errors and constraint of perpendicular mesh subdivision, since we excluded a finite difference approximation of vorticity on no‐slip boundaries. A considerable effect of upwind weighting function was examined. The method was successfully applied to a problem of natural convection around a horizontal hot cyl

ISSN:0271-2091    

DOI:10.1002/fld.1650030502

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe quasi‐three‐dimensional equations controlling the groundwater flow in heterogeneous and interconnected aquifer systems are discretized by finite elements, considering also the aquifer branching. A new method for fluid mass balance evaluation based on the equivalent nodal source (E.N.S.) concept allows one to express the balance in conservative terms, and interpret finite element equations as nodal balance equations. The solution of the system is based on the frontal method. Use of substructures limits the frontal increase in correspondence to the aquifer branching. In the steady state, the frontal method is integrated with an iterative solution technique to eliminate the frontal increase caused by the presence of aquitards. It converges very rapidly, using a forcing technique with an automatic parameter definition. In the unsteady case the same scope is achieved using a predictor‐corrector procedure which employs the Crank‐Nicolson method in the corrector phase.This very stable procedure permits use of fairly long time‐steps and concerns the case of source terms depending on piezometry (problem of interaction between water table and river). This method has been tested with several fairly comp

ISSN:0271-2091    

DOI:10.1002/fld.1650030503

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe bbundary integral formulation and boundary element method are extended to include lifting flow problems. This involves inclusion of a branch cut in the flow field and imposition of a Kutta condition to determine the circulation, Γ Additional boundary integral contributions arise from the cut surface. Techniques for calculating Γ are developed and we treat, in particular, a superposition procedure which permits very efficient computation. Numerical results are presented for an NACA0012 aerofoil at several angles of attac

ISSN:0271-2091    

DOI:10.1002/fld.1650030504

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA revised version of Dodge's split‐velocity method for numerical calculation of compressible duct flow has been developed. The revision incorporates balancing of mass flow rates on each marching step in order to maintain front‐to‐back continuity during the calculation. The (chequerboard) zebra algorithm is applied to solution of the three‐dimensional continuity equation in conservative form. A second‐order A‐stable linear multistep method is employed in effecting a marching solution of the parabolized momentum equations. A chequerboard iteration is ued to solve the resulting implicit non‐linear systems of finite‐difference equations which govern stepwise transition. Qualitive agreement with analytical predictions and experimental results has been obtained for some flows with well

ISSN:0271-2091    

DOI:10.1002/fld.1650030505

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractFinite element models are presented for the calculation of near and far field acoustical radiation. These models are applied to the specific problem of fan noise radiation from axisymmetric turbofan inlets. In all cases conventional acoustic finite elements are used within an inner region close to the inlet. The far field is represented by infinite elements or wave envelope elements. Theory and results are presented for the case with zero mean flow. Comparisons of computed data with analytic solutions and measured values establish the utility of both the infinite element and wave envelope element schemes in determining the near field values of acoustical pressure. The wave envelope scheme is shown to be effective also in the far field. Both schemes use meshes an order of magnitude more sparse that would be required in conventional numerical discretizations, and may consequently be applied at modest computational cost.

ISSN:0271-2091    

DOI:10.1002/fld.1650030506

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650030507

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650030501

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY