Advances in Engineering Software 95 (2016) 51–67
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Advances in Engineering Software
journal homepage: www.elsevier.com/locate/advengsoft
The Whale Optimization Algorithm
Seyedali Mirjalili
a
,
b
,
∗
, Andrew Lewis
a
a
School of Information and Communication Technology, Griffith University, Nathan Campus, Brisbane, QLD 4111, Australia
b
Griffith College, Mt Gravatt, Brisbane, QLD 4122, Australia
a r t i c l e i n f o
Article history:
Received 7 August 2015
Revised 8 January 2016
Accepted 15 January 2016
Keywords:
Optimization
Benchmark
Constrained optimization
Particle swarm optimization
Algorithm
Heuristic algorithm
Genetic algorithm
Structural optimization
a b s t r a c t
This paper proposes a novel nature-inspired meta-heuristic optimization algorithm, called Whale Opti-
mization Algorithm (WOA), which mimics the social behavior of humpback whales. The algorithm is in-
spired by the bubble-net hunting strategy. WOA is tested with 29 mathematical optimization problems
and 6 structural design problems. Optimization results prove that the WOA algorithm is very competi-
tive compared to the state-of-art meta-heuristic algorithms as well as conventional methods. The source
codes of the WOA algorithm are publicly available at http://www.alimirjalili.com/WOA.html
©2016 Elsevier Ltd. All rights reserved.
1. Introduction
Meta-heuristic optimization algorithms are becoming more and
more popular in engineering applications because they: (i) rely
on rather simple concepts and are easy to implement; (ii) do not
require gradient information; (iii) can bypass local optima; (iv)
can be utilized in a wide range of problems covering different
disciplines.
Nature-inspired meta-heuristic algorithms solve optimization
problems by mimicking biological or physical phenomena. They
can be grouped in three main categories (see Fig. 1 ): evolution-
based, physics-based, and swarm-based methods. Evolution-based
methods are inspired by the laws of natural evolution. The search
process starts with a randomly generated population which is
evolved over subsequent generations. The strength point of these
methods is that the best individuals are always combined together
to form the next generation of individuals. This allows the popu-
lation to be optimized over the course of generations. The most
popular evolution-inspired technique is Genetic Algorithms (GA)
[1] that simulates the Darwinian evolution. Other popular algo-
rithms are Evolution Strategy (ES) [110] , Probability-Based Incre-
mental Learning (PBIL) [ 111] , Genetic Programming (GP) [2] , and
Biogeography-Based Optimizer (BBO) [3] .
∗
Corresponding author. Tel.: + 61 434555738.
E-mail address: seyedali.mirjalili@griffithuni.edu.au , ali.mirjalili@gmail.com
(S. Mirjalili).
Physics-based methods imitate the physical rules in the uni-
verse. The most popular algorithms are Simulated Annealing (SA)
[4,5] , Gravitational Local Search (GLSA) [6] , Big-Bang Big-Crunch
(BBBC) [7] , Gravitational Search Algorithm (GSA) [8] , Charged
System Search (CSS) [9] , Central Force Optimization (CFO) [10] ,
Artificial Chemical Reaction Optimization Algorithm (ACROA)
[11] , Black Hole (BH) [12] algorithm, Ray Optimization (RO) [13]
algorithm, Small-World Optimization Algorithm (SWOA) [14] ,
Galaxy-based Search Algorithm (GbSA) [15] , and Curved Space
Optimization (CSO) [16] .
The third group of nature-inspired methods includes swarm-
based techniques that mimic the social behavior of groups of ani-
mals. The most popular algorithm is Particle Swarm Optimization,
originally developed by Kennedy and Eberhart [17] . PSO is inspired
by the social behavior of bird flocking. It uses a number of par-
ticles (candidate solutions) which fly around in the search space
to find the best solution ( i.e. the optimal position). Meanwhile,
they all trace the best location (best solution) in their paths. In
other words, particles consider their own best solutions as well as
the best solution the swarm has obtained so far. Another popular
swarm-based algorithm is Ant Colony Optimization, first proposed
by Dorigo et al. [18] . This algorithm is inspired by the social be-
havior of ants in an ant colony. In fact, the social intelligence of
ants in finding the closest path from the nest and a source of food
is the main inspiration of this algorithm. A pheromone matrix is
evolved over the course of iteration by the candidate solutions.
Other swarm-based techniques are listed in Table 1 . This class
of meta-heuristic methods started to be attractive since PSO was
http://dx.doi.org/10.1016/j.advengsoft.2016.01.008
0965-9978/© 2016 Elsevier Ltd. All rights reserved.