دراسة الضغط المستحث بالرياح على سقف جملوني منخفض الميل بزاوية 8 درجات باستخدام الفحوصات المختبرية والمحاكاة العددية
محتوى المقالة الرئيسي
الملخص
يهدف هذا البحث إلى دراسة الضغوط المستحثة بالرياح على سقف جملوني منخفض الميل بزاوية 8 درجات باستخدام اختبارات نفق الرياح والمحاكاة العددية ببرنامج ANSYS Fluent. يمثل السقف المدروس أحد أشكال أسقف المباني المنخفضة الارتفاع وفق تصنيف ASCE/SEI 7. تم فحص أربع حالات للسقف، شملت السقف المغلق، والسقف ذي فتحة واحدة، والسقف ذي الفتحتين، والسقف ذي الأربع فتحات. أجريت الاختبارات المختبرية تحت الظروف نفسها داخل نفق رياح مفتوح الدائرة في كلية الهندسة، جامعة بغداد، وبسرعة رياح مرجعية ثابتة مقدارها 38 م/ثا. تم قياس الضغوط السطحية باستخدام نقاط ضغط موزعة على الجدار المواجه للرياح، والجدار الخلفي، وسطوح السقف الجملوني، ثم حُسبت معاملات الضغط المناظرة. كما تم بناء نموذج عددي ثلاثي الأبعاد باستخدام صياغة RANS للجريان المستقر غير القابل للانضغاط في ANSYS Fluent 2025 R1 مع نموذج الاضطراب القياسي k–ε. أظهرت النتائج أن زيادة عدد الفتحات في السقف أدت إلى تعزيز التفاعل بين الجريان المنفصل الخارجي والحجم الهوائي الداخلي، مما سبب إعادة توزيع واضحة للضغط على سطح السقف. كما أظهرت نتائج المحاكاة العددية توافقاً جيداً جداً مع القياسات المختبرية، إذ بلغت قيمة معامل التحديد R² = 0.996، بينما بلغت RMSE ≈ 0.069 وME ≈ 0.051. وتشير النتائج إلى أن فتحات السقف تؤثر بشكل ملحوظ في الاستجابة الديناميكية الهوائية لضغوط الرياح على الأسقف الجملونية المنخفضة الارتفاع، لذلك ينبغي أخذها بنظر الاعتبار عند تقييم ضغوط الرياح المؤثرة على الأسقف.
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