Numerical investigation of propeller flow field using mrf model

Öz

This research employs computational fluid dynamics to examine the velocity field and bed shear stress produced by a propeller jet. A steady-state MRF approach was utilized to approximate the propeller’s swirling. 10 inflation layers were applied at both the propeller and the seabed to better enhance the resolution of the near-wall gradients. Model sensitivity to turbulence-model selection was evaluated by testing the SST and the realizable k-ε models. The findings indicated that both models effectively simulated the overall jet structure and shear footprint, yet they exhibited differences in detail: the k-ε model estimated a higher shear stress value of ~0,11 Pa with a broader scour pattern, whereas the SST model maintained a narrower jet core and a more concentrated vortex with shear stress maxima of ~0,078 Pa. The results indicate the importance of selecting appropriate mesh configurations and turbulence models for accurately predicting propeller jet scours.

Anahtar Kelimeler

• Propeller jet
• Wall shear stress
• CFD
• Turbulence modelling

Pervane akım alanının mrf modeli ile sayısal analizi

Öz

Bu araştırma, hesaplamalı akışkanlar dinamiğini kullanarak pervane jeti ile oluşan hız alanı ve taban kayma gerilimesini incelemektedir. Pervanenin çevri hareketini yaklaşık olarak hesaplamak için kararlı akım koşullarında MRF yaklaşımı kullanılmıştır. Taban yakınındaki sınır tabakası çözünürlüğünü daha iyi elde edebilmek için hem pervaneye hem de tabana 10 kademeli çözüm ağı uygulanmıştır. Türbülans modelinin duyarlılığı, SST ve gerçekleştirilebilir k-ε modellerini test ederek değerlendirilmiştir. Bulgular, her iki modelin de genel jet yapısını ve taban kayma gerilmesi izini etkili bir şekilde benzeştirdiğini, ancak ayrıntılarda farklılıklar gösterdiğini ortaya koymuştur: k-ε modeli, daha geniş bir oyulma modeliyle ~0,11 Pa'lık daha yüksek bir kayma gerilimi değeri elde ederken, SST modeli daha dar bir jet çekirdek alanı ile daha yoğun bir çevri bölgesi ve ~0,078 Pa'lık maksimum kayma gerilimi belirlemiştir. Sonuçlar pervane jeti kaynaklı oyulmalarını doğru bir şekilde belirlemek için uygun ağ konfigürasyonları ve türbülans modellerinin seçilmesinin önemini göstermektedir.

Anahtar Kelimeler

• Pervane jeti
• Taban kayma gerilmesi
• HAD
• Türbülans modelleme

Kaynakça

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