115 citations · 537 across the 22 of their papers we have counts for
22 papers
Causality analysis of large-scale structures in the flow around a wall-mounted square cylinder
Álvaro Martínez-Sánchez, Esteban López, Soledad Le Clainche +3
The aim of this work is to analyse the formation mechanisms of large-scale coherent structures in the flow around a wall-mounted square cylinder, due to their impact on pollutant t…
Spectral extended finite element method for band structure calculations in phononic crystals
Eric B. Chin, Amir Ashkan Mokhtari, Ankit Srivastava +1
In this paper, we compute the band structure of one- and two-dimensional phononic composites using the extended finite element method (X-FEM) on structured higher-order (spectral)…
Causality and Passivity: from Electromagnetism and Network Theory to Metamaterials
Ankit Srivastava
In this review, we take an extensive look at the role that the principles of causality and passivity have played in various areas of physics and engineering, including in the moder…
Scattering under Linear Non Self-Adjoint Operators: Case of in-Plane Elastic Waves
Amir Ashkan Mokhtari, Yan Lu, Qiyuan Zhou +2
In this paper, we consider the problem of the scattering of in-plane waves at an interface between a homogeneous medium and a metamaterial. The relevant eigenmodes in the two regio…
On the Properties of Phononic Eigenvalue Problems
Amir Ashkan Mokhtari, Yan Lu, Ankit Srivastava
In this paper, we consider the operator properties of various phononic eigenvalue problems. We aim to answer some fundamental questions about the eigenvalues and eigenvectors of ph…
On the Emergence of Negative Effective Density and Modulus in 2-phase Phononic Crystals
Amir Ashkan Mokhtari, Yan Lu, Ankit Srivastava
In this paper we report metamaterial properties including negative and singular effective properties for what would traditionally be considered non locally resonant 2-phase phononi…
Level Repulsion and Band Sorting in Phononic Crystals
Yan Lu, Ankit Srivastava
In this paper we consider the problem of avoided crossings (level repulsion) in phononic crystals and suggest a computationally efficient strategy to distinguish them from normal c…
Acoustic Filter Design Using Temperature Tuning
Hossein Sadeghi, A. Srivastava, A. V. Amirkhizi +1
The material properties selection for designing acoustic filters with optimal performance over a range of frequencies requires considerable effort to fabricate and test laboratory…
Evanescent Wave Boundary Layers in Metamaterials and Sidestepping them through a Variational Approach
Ankit Srivastava, John R. Willis
All metamaterial applications are based upon the idea that extreme material properties can be achieved through appropriate dynamic homogenization of composites. This homogenization…
Negative Refraction, Beam Steering, Mode Switching, and High-pass Filtering in a 1-D Periodic Laminate
Ankit Srivastava
In this paper we show that a 1-D phononic crystal (laminate) can exhibit metamaterial wave phenomenon which is traditionally associated with 2-, and 3-D crystals. Moreover, due to…
Variational Methods For Phononic Calculations
Yan Lu, Ankit Srivastava
Three fundamental variational principles used for solving elastodynamic eigenvalue problems are studied within the context of elastic wave propagation in periodic composites (phono…
Combining plane wave expansion and variational techniques for fast phononic computations
Yan Lu, Ankit Srivastava
In this paper the salient features of the Plane Wave Expansion (PWE) method and the mixed variational technique are combined for the fast eigenvalue computations of arbitrarily com…
3-D phononic crystals with ultra-wide band gaps
Yan Lu, Yang Yang, James K. Guest +1
In this paper gradient based topology optimization (TO) is used to discover 3-D phononic structures that exhibit ultra-wide normalized all-angle all-mode band gaps. The challenging…
Causality and Passivity in Elastodynamics
Ankit Srivastava
What are the constraints placed on the frequency dependent constitutive tensors of elastodynamics by the requirements that the linear elastodynamic system under consideration be bo…
On the Limit and Applicability of Dynamic Homogenization
Ankit Srivastava, Sia Nemat-Nasser
Recent years have seen considerable research success in the field of dynamic homogenization which seeks to define frequency dependent effective properties for heterogeneous composi…
Mixed-variational formulation for phononic band-structure calculation of arbitrary unit cells
Ankit Srivastava, Sia Nemat-Nasser
This paper presents phononic band-structure calculation results obtained using a mixed variational formulation for 1-, and 2-dimensional unit cells. The formulation itself is prese…
Elastic Metamaterials and Dynamic Homogenization: A Review
Ankit Srivastava
In this paper we review the recent advances which have taken place in the understanding and applications of acoustic/elastic metamaterials. Metamaterials are artificially created c…
From Newton's Universal Gravitation to Einstein's Geometric Theory of Gravity
Donald H. Kobe, Ankit Srivastava
Starting with Newton's law of universal gravitation, we generalize it step-by-step to obtain Einstein's geometric theory of gravity. Newton's gravitational potential satisfies the…
Bounds on Effective Dynamic Properties of Elastic Composites
Sia Nemat-Nasser, Ankit Srivastava
We present general, computable, improvable, and rigorous bounds for the total energy of a finite heterogeneous volume element or a periodically distributed unit cell of an elastic…
Universal Theorems for Total Energy of the Dynamics of Linearly Elastic Heterogeneous Solids
Ankit Srivastava, Sia Nemat-Nasser
In this paper we consider a sample of a linearly elastic heterogeneous composite in elastodynamic equilibrium and present universal theorems which provide lower bounds for the tota…
Overall Dynamic Properties of 3-D periodic elastic composites
Ankit Srivastava, Sia Nemat-Nasser
A method for the homogenization of 3-D periodic elastic composites is presented. It allows for the evaluation of the averaged overall frequency dependent dynamic material constitut…
Overall Dynamic Constitutive Relations of Micro-structured Elastic Composites
Sia Nemat-Nasser, Ankit Srivastava
A method for homogenization of a heterogeneous (finite or periodic) elastic composite is presented. It allows direct, consistent, and accurate evaluation of the averaged overall fr…