About

Jack J. McNamara is a professor in the Department of Mechanical & Aerospace Engineering at The Ohio State University. His research interests are broadly in the areas of fluid-structural interactions and model reduction of high-dimensional dynamical systems, with an interconnected goal of improving basic understanding and computational methods. A core application target is air vehicle operation in high-speed flow regimes, where there is a potential for complex interactions at both the component (fluid-thermal-structural-material) and vehicle (aero-servo-thermo-elastic-propulsive) levels. Other application areas include fluid-structural centric problems associated with ship airwakes, wind turbines, flapping wing air vehicles, automobiles, and turbomachinery. He is the director of the Multi-Physics Interactions Research Group (MIRG) at The Ohio State University.

Research topics

• Physics
• Mechanics
• Structural engineering
• Engineering
• Materials science
• Optics

Selected publications

• Temporal convergence analysis of the generalized finite element method for multi-scale heat transfer

  Computer Methods in Applied Mechanics and Engineering · 2026-02-13

  articleSenior author
  PublisherDOI

• Modeling Fluid–Thermal Coupling in Gap Regions of High-Speed Control Surfaces

  AIAA Journal · 2026-01-27

  article

  The gap region of all-movable control surfaces on high-speed vehicles involves complex flow conditions and extreme aerodynamic heating. This study models fluid–thermal coupling in such problems. A global–local decomposition procedure is implemented to manage disparate length scales in the gap region. The fluid–thermal coupling uses boundary condition exchange between a finite volume computational fluid dynamics solver and a finite element thermal solver. Two standard boundary conditions are considered: 1) direct heat flux from the fluid solver and 2) a film boundary condition that incorporates the heat transfer coefficient and adiabatic wall temperature. Results demonstrate that the common heat flux boundary condition can lead to unstable transient thermal solutions and degraded time accuracy if naively implemented with an implicit time integrator. Conversely, the film boundary condition maintains unconditional stability. Additionally, the impact of exchange frequency between fluid and thermal solvers is assessed in terms of computational expense and accuracy. Results highlight the coupled fluid–thermal response in the gap region, with peak surface heating rates up to 50 times baseline values and surface temperatures exceeding 1400 K. A long-duration thermal response of the gap region indicates peak temperatures in the substructure up to 700 K and strong thermal gradients.

  PublisherDOI

• Assessment of aeroelastic coupling between a shock boundary layer interaction and a flexible panel

  Journal of Fluids and Structures · 2025-02-07 · 6 citations

  articleCorresponding
  PublisherDOI

• Temporal Convergence Analysis of the Generalized Finite Element Method for Multi-Scale Heat Transfer

  SSRN Electronic Journal · 2025-01-01 · 1 citations

  preprintOpen accessSenior author
  PublisherDOI

• Basis Identification for Nonlinear Dynamical Systems Using Sparse Coding

  River Publishers eBooks · 2025-08-07

  book-chapterSenior author

  Basis identification is a critical step in the construction of accurate reduced order models using Galerkin projection. This is particularly challenging in unsteady nonlinear flow fields due to the presence of multi-scale phenomena that cannot be ignored and are not well captured using the ubiquitous Proper Orthogonal Decomposition. This study focuses on this issue by exploring an approach known as sparse coding for the basis identification problem. Compared to Proper Orthogonal Decomposition, which seeks to truncate the basis spanning an observed data set into a small set of dominant modes, sparse coding is used to select a compact basis that best spans the entire data set. Thus, the resulting bases are inherently multi-scale, enabling improved reduced order modeling of unsteady flow fields. The approach is demonstrated for a canonical problem of an incompressible flow inside a 2-D lid-driven cavity. Results indicate that Galerkin reduction of the governing equations using sparse modes yields significantly improved fluid predictions.

  PublisherDOI

• Resolvent Analysis for Insights into Laminar Shock-Boundary Layer Interactions Over Deforming Surfaces

  2025-01-03 · 7 citations

  article

  A laminar shock-boundary layer interaction (SBLI) at M = 2, Re_a = 120,000, and p_3/p_1 = 1.5 is investigated numerically to gain insights for flow control and fluid-structure interaction (FSI). The approach involves a resolvent analysis of the base flow followed by large eddy simulations (LES) embedded with disturbances derived from the resolvent forcing modes. The resolvent analysis is used first to extract the optimal forcing/response properties of the Kelvin-Helmholtz (K-H) instability in the separated shear layer, whose modulation is known to enable separation bubble control and may play an important role in the fluid-structural coupling between SBLI and compliant surfaces. A forcing strategy is devised from the resolvent forcing modes to inform an LES campaign. The forcing is applied via either surface transpiration or surface deformation, yielding separation length reductions of up to 100% and 45.8%, respectively. Analysis of the forced flow confirms the presence of spanwise roller structures that enhance entrainment in the shear layer, indicative of the classical K-H separation control mechanism. Exploring links between the resolvent analysis and published FSI literature revealed the potential for exploiting such a mechanism for flow control via compliant surfaces. The effect of a time-mean surface deflection is also found to be inconsequential for separation control.

  PublisherDOI

• Interaction Between Aerothermally Compliant Structures and Boundary Layer Transition

  River Publishers eBooks · 2025-08-07

  book-chapterSenior author

  The inherent relationship between boundary layer stability, aerodynamic heating, and surface conditions make the potential for interaction between the structural response and boundary layer transition an important and challenging area of study in high speed flows. This interdependence implies that accurate structural response prediction of a hypersonic vehicle necessitates an aerothermoelastic analysis that accounts for boundary layer stability in regions where transition is likely to occur. This study focuses on this problem by incorporating a time-varying boundary layer state into the aerothermoelastic response prediction of a structural panel in hypersonic flow. Results demonstrate that rearward movement of the boundary layer transition front reduces thermal loading to the panel and peak deformation, potentially extending the life of the structure.

  PublisherDOI

• Turbulent Shock-Wave Boundary Layer Interactions Over Compliant Panels: Insights from One-Way Analyses

  Journal of Fluids and Structures · 2025-01-01 · 1 citations

  articleOpen access

  Panels encountering low-frequency loading due to proximal turbulent shock-wave boundary layer interactions (SWBLI) experience fluid structure interactions (FSI), with adverse and potentially catastrophic effects on high-speed vehicle performance. In certain parameter ranges, the feedback between fluid and structure is muted, and one-way analyses offer computational efficiency for rapid assessments of prescribed fluid load on the structural response (F→S) and vice versa, i.e., prescribed structural motion on fluid response (S→F). Both scenarios are examined here for a Mach 2 SWBLI over a 22.5o ramp, using Large-Eddy Simulations for the fluid and a finite-element model for the structure. Where possible, the literature on experimental observations and coupled simulations validate the appropriateness of the approach. In the F→S framework, the effects of precomputed turbulent surface pressures are examined on different panels; parameters varied include cavity pressure, boundary conditions (pinned/clamped), frequency alignment with structural modes, panel orientation, and location relative to the interaction. When placed near flow separation, panel responses exhibit distinct features including effective stiffening under elevated cavity pressure, emergence of asymmetric modes for oblique orientations, and mode selectivity influenced by spatial and spectral alignment with shock-induced features. When placed near reattachment, higher-order panel modes are excited, driven by shear layer impingement. In the S→F framework, the panel is placed near separation, with its motion conforming to mid-frequency scales. The flow response exhibits significant intermittency in separation/reattachment, reduced time-mean skin friction, attenuation of low-frequency content, and increase separation extent due to downstream movement of the reattachment point. Lagrangian modal analyses associate these effects with shock modulation by panel-induced intermittent shocklets.

  PublisherDOI

• Fluid-Structure Interaction Insights From Pressure-Sensitive Paint Measurements for Double-Fin SBLI

  2025-01-03 · 2 citations

  article

  Fluid-structure interactions (FSI) induced by shock-wave/boundary layer interactions (SBLI) significantly influence the design and performance of high-speed vehicles. Two-way FSI simulations, though comprehensive, pose significant computational challenges. One-way fluid-to-structure (F→S) interactions, while capturing only a subset of the complete physical dynamics, can provide important insights in a far more economical manner. In this study, we examine compliant panel response to 3D compound swept SBLI, specifically double-fin (or crossing-shock) SBLI. Experimental time-resolved pressure-sensitive paint (PSP) measurements on a rigid wall beneath the compound interaction reveal a region of relatively low-frequency pressure fluctuations. These turbulent pressure loads are subsequently imposed on a panel, eliciting a range of responses by varying the panel compliance. Geometric non-linear structural responses are analyzed in phase-space and intermodal interactions among different panel modes using high-order system identification techniques. Beyond a critical threshold, the panel response is characterized by the existence of multiple limit cycles, exhibiting large and small amplitude oscillations, consistent with non-linear structural behaviors previously documented in the literature for simplified loading conditions. This study demonstrates the utility of PSP data in parametric FSI analyses to comprehend the conditions under which non-linear behavior becomes significant.

  PublisherDOI

• Resolvent Analysis for Insights into Laminar Shock/Boundary Layer Interactions over Deforming Surfaces

  AIAA Journal · 2025-09-22

  article

  A laminar shock/boundary layer interaction (SBLI) at [Formula: see text], [Formula: see text], and [Formula: see text] is investigated numerically to gain insights for flow control and fluid–structure interaction (FSI). The approach involves a resolvent analysis of the base flow followed by large eddy simulations (LESs) embedded with disturbances derived from the resolvent forcing modes. The resolvent analysis is used first to extract the optimal forcing/response properties of the Kelvin–Helmholtz (K-H) instability in the shear layer, whose modulation is known to enable separation control and may play a role in the fluid–structural coupling between SBLI and compliant surfaces. A forcing strategy is devised from the resolvent forcing modes to inform an LES campaign. Forcing is applied via either surface transpiration or surface deformation, yielding separation length reductions of up to 100 and 45.8%, respectively. Analysis of the forced flow confirms the presence of spanwise rollers that enhance entrainment in the shear layer, indicative of the classical [Formula: see text] separation control mechanism. Exploring links between the resolvent analysis and published FSI literature reveals the potential for exploiting such a mechanism for flow control via compliant surfaces. The effect of a time-mean surface deflection is also found to be inconsequential for separation control.

  PublisherDOI

Frequent coauthors

• Peretz P. Friedmann

  University of Michigan–Ann Arbor

  53 shared

• Andrew Crowell

  Virginia Commonwealth University

  37 shared

• Adam Culler

  Sierra Lobo (United States)

  35 shared

• Datta V. Gaitonde

  28 shared

• Rohit Deshmukh

  24 shared

• Biju J. Thuruthimattam

  University of Michigan–Ann Arbor

  20 shared

• Brent A. Miller

  The Ohio State University

  20 shared

• Kenneth G. Powell

  University of Michigan–Ann Arbor

  19 shared