報告書番号

U97071

タイトル（和文）

並列計算による放水路合流・分岐部の数値水理設計

タイトル（英文）

COMPUTER-AIDED HYDRAULIC DESIGN OF A COOLING-WATER DISCHARGE SYSTEM BASED ON MULTIBLOCK-PARALLEL COMPUTATIONS

概要 （図表や脚注は「報告書全文」に掲載しております）

複雑な発電所水理構造物形状を取り扱うことが可能であり，しかも並列計算により計算時間を大幅に短縮化できる流体解析手法を開発するため，領域分割・並列流体解析手法を開発した。この手法では，対象領域を分割し，その結果単純化された各ブロックの境界形状を３次元境界適合座標系で表現する。座標生成と流体解析は，ブロックごとに並列的に進める。流体計算には，ラグランジュスキームに基づく高精度の流体解析手法を適用する。解析手法の適用性を確認するため，発電所放水路系を３つのブロックに分割して，全体の構造物形状を正確に表現し，３次元流況と２本の放水路の流量配分などを並列計算により求めた。その結果，放流水の流入条件の違いにより，放水路合流部には複雑な流況が発生するが，２本の放水路の流量差は，全流量の１割以下であることが示された。この流量配分の計算結果は，放水路系の１次元概略計算の値とも概ね一致する。

概要 （英文）

A NEW COMPUTATIONAL METHOD HAS BEEN DEVELOPED TO PREDICT 3D FLUID DYNAMICS IN COMPLEX HYDRAULICS STRUCTURES BASED ON MULTIBLOCK GRIDS AND PARALLEL COMPUTATION. A 3D COMPUTATIONAL DOMAIN,WHICH MAY HAVE COMPLEX GEOMETRIES,IS BROKEN DOWN INTO MULTIPLE BLOCKS USING ARBITRARY SURFACES. THE 3D BODY-FITTED COORDINATES (3D BFC) ARE GENERATED FOR EACH OBTAINED BLOCK,WHICH HAS SIMPLER BOUNDARY SHAPES DUE TO THE BREAK DOWN. THEREFORE,THE PRESENT COMPUTATIONAL METHOD ALLOWS US TO DEAL WITH A COMPUTATIONAL DOMAIN THAT HAS MUCH MORE COMPLEX GEOMETRIES,SUCH AS PIPING SYSTEMS AND A SERIES OF THE CNNECTED HYDRAULICS STRUCTURES,THAT CANNOT BE MAPPED BY 3D BFC BASED ON THE USUAL SINGLE-BLOCK TREATMENT. THE GRID GENERATION AND COMPUTATION OF FLUID DYNAMICS IN EACHBLOCK PROCEED INDEPENDENTLY UTILIZING A WORKSTATION NETWORK AS A PARALLEL COMPUTER BASED ON MPI (MESSAGE-PASSING INTERFACE). TO EXCHANGE THE DATA LOCATED NEAR THE COMMON BOUNDARIES SHARED BY MULTIPLE BLOCKS EFFICIENTLY,A MASTER-SLAVE MODEL IS USED. THE DATA CALCULATED BY THE SLAVE PROCESS IN EACH BLOCK ARE TRANSFERRED TO THE MASTER PROCESS WHERE SPATIAL INTERPOLATION AND OTHER NUMERICAL PROCEDURES ARE APPLIED. THE MASTER PROCESS THEN DISTRIBUTES THE DATA TO MULTIPLE SLAVE PROCESSES. THE DEVELOPED METHOD WAS APPLIED TO A COOLING-WATER DISCHARGE SYSTEM IN A POWERSTATION CONSISTING OF A COOLING-WATER POOL AND TWO WATER CHANNELS. THIS COMPUTATIONAL DOMAIN WAS BROKEN DOWN INTO THREE BLOCKS WITH A SPEED-UP RATIO OF 2.3. AT PARALLEL COMPUTATION WITH VARIOUS INLET BOUNDARY CONDITIONS,THE 3D FLOW PATTERNS WERE PREDICTED IN THE POOL AND THE FLOW-RATE DISTRIBUTIONS IN THE TWO CHANNELS WERE EVALUATED. THE PREDICTED FLOW-RATE DISTRIBUTIONS WERE OF THE SAME ORDER AS CALCULATED BY 1D NETWORK MODELS.

報告者

キーワード