Validation of short-term prediction of added resistance in head seas considering wave steepness nonlinearity with probability density function method

• Published in: Ocean engineering Vol. 278; p. 114353
• Main Authors: Jawa, Sahil, Munehiko, Minoura
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.06.2023
• Subjects: Added resistance; CFD; Head seas; Long crested irregular waves; Model tank tests; Non-linearity; Regular waves; RIOS containership; Wave steepness; CFD; Non-linearity; Long crested irregular waves; Regular waves; Head seas; Added resistance; RIOS containership; Wave steepness; Model tank tests
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2023.114353

The added resistance in waves, which is an important component in the estimation of actual sea performance of ships, has been evaluated as the average value by short-term prediction methods. In this paper, a novel probabilistic method to account for non-linearities of added resistance with respect to wave height in short-term sea conditions is proposed using the joint occurrence probability distribution of wave height and period and non-linear added resistance response in the frequency region. It is a method of averaging the combination of crest and trough that ships encounter in irregular waves, which is considered as one wave of the regular waves, and the resulting added resistance is combined stochastically. The non-linearity with respect to wave height is empirically expressed as a “correction coefficient” obtained from the comparison of CFD data and potential-based linear calculation results in regular waves. The results of the proposed method have a reasonable agreement in the acceptable range of accuracy with results of RANSE based CFD numerical simulations in long crested irregular waves and the experimental model tests. As a result, the proposed method is applicable for obtaining added resistance in irregular head waves having the non-linearity with respect to wave height with a scope of further improvement in the method. •Calculating the correction coefficient C(s) for non-linearity in added wave resistance with respect to wave height squared using the CFD calculations in regular head waves.•A modification in the Longuet-Higgins joint occurrence of wave height-wave period probability model is proposed.•A probability density function method has been developed for estimating the added resistance in irregular waves by combining the nonlinearity of added resistance due to wave steepness.•The spectrum method shows a better agreement with the experimental results and CFD results as compared to Probability density function method as the non-linear PDF method underestimated values in T01/TL≤1 and overestimated values in the range T01/TL>1 for two different significant wave heights. The proposed PDF model should be further improved.