報告書番号

380058

タイトル（和文）

海浜流を考慮した温排水拡散予測－予測結果と実験結果との比較－

タイトル（英文）

PREDICTION OF THE DIFFUSION OF DISCHARGED WARM WATER INFLUENCED BY NEARSHORE CURRENTS -COMPARISON BETWEEN THE RESULTS BY THE NUMERICAL SIMULATION AND THE EXPERIMENTAL RESULTS-

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究は，海浜流を考慮した温排水拡散予測のための研究の第一段階として，波浪影響下の温排水拡散に関する水理模型実験で用いたのと同じ地形，沖合波浪，温排水放流条件のもとで，従来の数理モデルを基本としたシミュレーション解析により海浜流速度場および海浜流影響下の小流量を対象とする温排水拡散範囲を予測し，実験結果との比較照合によって数理モデルの妥当性，問題点を検討したものである。得られた知見は以下のとおりである。１．海浜流流況の再現性：平常時規則波作用下の海浜流流況計算結果は，大局的に見て実験結果の流況パターンをほぼ再現するが，流速自体は大きめであり，モデルの改良が必要である。２．水温上昇範囲の再現性：平常波作用時の１℃水温上昇範囲については，計算結果は実験結果をかなり良く再現するが，２℃以上の高温度上昇範囲については，実験結果に比べて小さくなり再現性は不十分なため，モデルの改良が必要である。

概要 （英文）

THE PRESENT STUDY IS CONSIDERED TO BE THE FIRST STEP IN ESTABLISHING A METHOD TO PREDICT THERMAL DIFFUSION RANGES INFLUENCED BY NEARSHORE CURRENTS AND WAVES.THE SAME CONDITIONS AS THOSE IN THE HYDRAULIC MODEL TESTS ARE SELECTED WITH REGARD TO SEA BOTTOM CONFIGURATION,REGULAR WAVES IN THE OFFING,AND WARMED WATER DISCHARGE.NUMERICAL SIMULATIONS BASED ON THE TRADITIONAL MODELS ARE CARRIED OUT CONCERNING THE VELOCITY VECTOR FIELD DUE TO NEARSHORE CURRENTS AND THE DIFFUSION RANGES OF A SMALL QUANTITY OF DISCHARGED WARM WATER UNDER THE EFFECT OF NEARSHORE CURRENTS.THEN,VALIDITY OF THE NUMERICAL MODEL IS EXAMINED BY COMPARING THE RESULTS OF THE NUMERICAL SIMULATION WITH THOSE OF THE HYDRAULIC MODEL TEST. THE INFORMATION OBTAINED BY THIS STUDY IS AS FOLLOWS. 1)REPRODUCIBILITY OF NEARSHORE CURRENTS:THE FLOW PATTERN OF NEARSHORE CURRENTS CALCULATED BY THE NUMERICAL SIMULATION COINCIDES ON THE WHOLE WITH THE EXPERIMENTAL RESULT.HOWEVER,THE RESULT OF THE NUMERICAL SIMULATION DIFFERS FROM THAT OF THE HYDRAULIC MODEL TEST IN LOCAL VELOCITY VECTORS AND THE FLOW SPEED GIVEN BY THE COMPUTATION IS APT TO BE LARGER.HENCE,IT IS NECESSARY TO IMPROVE THE MODEL OF NEARSHORE CURRENTS. 2)REPRODUCIBILITY OF THE HORIZONTAL DISTRIBUTION OF WATER TEMPERATURE RISE: AS FOR THE RANGE WHERE WATER TEMPERATURE IS MORE THAN 1 DEGREE C HIGHER THAN THAT OF THE AMBIENT WATER UNDER THE ACTION OF ORDINARY WAVES,THE NUMERICAL SIMULATION CAN REPRODUCE THE EXPERIMENTAL RESULT FAIRLY WELL.HOWEVER,WITH REGARD TO THE RANGE WHERE WATER TEMPERATURE IS MORE THAN 2 DEGREE C HIGHER THAN THAT OF THE AMBIENT WATER,THE NUMERICAL RESULT IS CONSIDERABLY SMALLER IN AREA THAN THE EXPERIMENTAL RESULT,AND REPRODUCIBILITY BY THE CALCULATION IS UNSATISFACTORY.HENCE,THE MODEL OF ADVECTIVE DIFFUSION OF WARMED WATER IS ALSO IN NEED OF IMPROVEMENT.

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