Isothermal Plane Research Articles

Can isothermal plane Couette flow in fluid overlying porous layer be linearly unstable?

The present study aims to examine the temporal linear stability analysis of isothermal plane Couette flow over a porous layer using the two-domain approach. The flow in the porous layer is described by the unsteady Darcy–Brinkman equations, whereas it is characterised by the Navier–Stokes equations in the fluid layer. In contrast to the Darcy model, it is observed that the isothermal plane Couette flow becomes unstable for such a superposed system on the inclusion of the Brinkman term. From the stability analysis, the two-dimensional mode is found to be least stable, and two modes of instability, namely porous mode and mixed mode are obtained under the consideration of the Darcy–Brinkman model along with advection term (DBA model). For Darcy number $(\delta )=0.01$ , depending on the value of the stress-jump coefficient, mixed mode controls the instability of the system at small values of depth ratio $(\hat {d})$ , and it disappears for relatively high values of $\hat {d}$ , where the porous mode dominates. In addition, it has been observed that when $\hat {d}=0.1$ , the critical mode of instability is found to be mixed for $\delta >0.02$ and porous for $\delta \le 0.02$ . The stress-jump coefficient destabilises the flow in terms of energy production through perturbed stresses at the interface. As observed in the case of isothermal plane Poiseuille flow studied by Chang, Chen & Straughan (J. Fluid Mech., vol. 564, 2006, pp. 287–303), here also depth ratio (Darcy number) stabilises (destabilises) the flow. However, this characteristic does not remain valid when the advection term is eliminated from the considered momentum equation. For a certain range of $\hat {d} (\delta )$ , the destabilising (stabilising) characteristic of the respective parameters are encountered when the fluid mode of instability prevails.

Thermal boundary conditions and rotation effects on the onset of casson fluid convection in a permeable layer produced by purely interior heating

In this work, we inspect the effect of thermal boundary conditions and rotation on the coming of Casson fluid convective motion generated by purely internal warming in a flat porous layer. Two types of thermal boundaries are utilized, namely, type (I) both boundary planes are isothermal and type (II) bottom boundary plane is insulated and top plane is isothermal. The altered Darcy model is used to characterize the rheological performance of Casson fluid movement in porous medium. The classical Horton–Rogers Lapwood stability examination is accomplished and the resultant eigenvalue problem is resolved numerically with the help of advanced-term Galerkin technique with the internal Rayleigh Darcy number as the eigenvalue. It is observed that the Taylor Darcy number has a stabilizing weight while the Casson parameter shows the dual influence on the system. The structure is more stable when both boundary planes are isothermal. The magnitude of the convection cells falls with increasing both the Taylor Darcy number and the Casson parameter. In the absence of Taylor Darcy number, the system’s stability decreases with the Casson parameter. Further, it is remarkable to observe that without rotation, the Casson parameter has no impression on the magnitude of convection cells.

Non-Isothermal Plane Couette Flow and Its Stability in an Anisotropic and Inhomogeneous Porous Layer Underlying a Fluid Layer Saturated by Water

Abstract In this article, the linear stability of nonisothermal plane Couette flow (NPCF) in an anisotropic and inhomogeneous porous layer underlying a fluid layer is investigated. The Darcy model is utilized to describe the flow in the porous layer. The stability analysis indicates that the introduction of media-anisotropy (K*) and media-inhomogeneity (in terms of inhomogeneity parameter A) still renders the isothermal plane Couette flow (IPCF) in such superposed fluid-porous systems unconditionally stable. For NPCF, three different modes, unimodal (porous or fluid mode), bimodal (porous and fluid mode) and trimodal (porous, fluid and porous mode), are observed along the neutral stability curves and characterized by the secondary flow patterns. It has been found that the instability of the fluid-porous system increases on increasing the media permeability and inhomogeneity along the vertical direction. Contrary to natural convection, at d̂=0.2 (d̂=depth of fluid layer/depth of porous layer) and K*=1, in which the critical wavelength shows both increasing and decreasing characteristics with increasing values of A (0≤A≤5), here in the present study, the same continuously decreases with increasing values of A. Finally, scale analysis indicates that the onset of natural convection requires a relatively higher temperature difference (ΔT) between lower and upper plates in the presence of Couette flow. However, by including media anisotropy and inhomogeneity in the porous media, the system becomes unstable even for a small critical temperature difference of about 2 °C.

On the role of low frequency modes in the thermal and momentum mixing in parallel plane jets

Parallel plane jet mixing has been the subject of extensive study and its physics are characterized well in literature. However, the physics of parallel plane jet mixing in relatively small confined regions is not well known. In this study we investigate the effects of re-circulatory flow on thermal and momentum mixing in confined parallel plane jets. Studying confined jet interaction is important for a variety of engineering applications. One of these applications is sodium cooled fast reactors (SFR). It is common in SFRs to have coolant stream mixing in a confined domain, often the upper plenum. The Reactor Cavity Cooling System (RCCS) facility at the University of Michigan models this problem in a simplified enclosure with isothermal parallel plane jets as the incoming coolant streams. A Large Eddy Simulation (LES) of this simplified plenum was developed using optimal boundary conditions, proven mesh convergence, and consistent resolution. This model was then validated against experimental results from the RCCS facility. After model validation, flow structures in the jet interaction were discerned by means of Proper Orthogonal Decomposition (POD). Comparison of 3D POD to a clipped 2D POD region reveals that re-circulatory flow can lead to dominant oscillations within the jet mixing region. Subsequently, Power Spectrum Density (PSD) and Continuous Wavelet Transforms (CWT) were used to ascertain frequency-based phenomena that might occur in this mixing region. Frequency analysis uncovered a dominant low-frequency oscillation in both velocity and temperature PSDs. These frequencies fall within the known ranges of thermal striping in sodium. The data generated in this study can be used for the benchmarking of less computationally intensive approaches. This data will be made available upon request to ebm5351@psu.edu.

Rayleigh waves in nonlocal generalized thermoelastic media

PurposeThe purpose of this article is to investigate the propagation characteristics (such as particle motion, attenuation and phase velocity) of a Rayleigh wave in a nonlocal generalized thermoelastic media.Design/methodology/approachThe bulk waves are represented with Helmholtz potentials. The stress-free insulated and isothermal plane surfaces are taken into account. Rayleigh wave dispersion relation has been established and is found to be complex. Due to the presence of radicals, the dispersion equation is continuously computed as a complicated irrational expression. The dispersion equation is then converted into a polynomial equation that can be solved numerically for precise complex roots. The extra zeros in this polynomial equation are eliminated to yield the dispersion equation’s roots. These routes are then filtered for inhomogeneous wave propagation that decays with depth. To perform numerical computations, MATLAB software is used.FindingsIn this medium, only one mode of Rayleigh wave exists at both isothermal and insulated boundaries. The thermal factors of nonlocal generalized thermoelastic materials significantly influence the particle motion, attenuation and phase velocity of the Rayleigh wave.Originality/valueNumerical examples are taken to examine how the thermal characteristics of materials affect the existing Rayleigh wave’s propagation characteristics. Graphical analysis is used to evaluate the behavior of particle motion (such as elliptical) both inside and at the isothermal (or insulated) flat surface of the medium under consideration.

Thermal Impact of 5G Antenna Systems in Sandwich Walls

The 5th generation (5G) cellular networks offer high speeds, low latency, and greater capacity, but they face greater penetration loss through buildings than 4G due to their higher frequency bands. To reduce this loss in energy-efficient buildings, a passive antenna system was developed and integrated into sandwich walls. However, the thermal effects of this system, which includes highly thermally conductive metals, require further study. In this research, three-dimensional heat transfer simulations were performed using COMSOL Multiphysics to determine the thermal transmittances (U-values) of 5G antenna walls. The results revealed that, using stainless steel as the connector material (current design), the U-value rose from 0.1496 (for the wall without antenna) to 0.156 W/m2K, leading to an additional heating loss per year of only 0.545 KWh/m2 in Helsinki. In contrast, with the previous design that used copper as the connector material, the U-value increased dramatically to 0.3 W/m2K, exceeding the National Building Code of Finland’s limit of 0.17 W/m2K and causing 12.8 KWh/m2 additional heat loss (23.5 times more than the current design). The current design significantly reduces thermal bridging effects. Additionally, three analytical methods were used to calculate antenna wall U-values: parallel paths, isothermal planes, and ISO 6946 combined. The isothermal planes method was found to be more accurate and reliable. The study also found that a wall unit cell with a single developed 5G antenna and a wall consisting of nine such cells arranged in a 3 × 3 grid pattern had the same U-values. Furthermore, areas affected by thermal bridging were typically smaller than the dimensions of a wall unit cell (150 mm × 150 mm).

Influence of temperature distribution on the foaming quality of foamed polypropylene composites

Abstract The foamed polypropylene (PP) composites were prepared by injection molding process. Fourier’s law and software were used to calculate and simulate the internal temperature distribution of PP composites, respectively, and the influence of the temperature distribution on the foaming quality of foamed PP composites was further analyzed. The result showed that the calculative and simulated results of temperature distribution in different thermal transfer directions had great reproducibility. In different isothermal planes, the temperature from the nozzle to the dynamic mold gradually decreased. The isothermal plane with a temperature of 370.36 K had a better foaming quality, average diameter of cell and cell density were 28.46 µm and 3.7 × 1010 cells·cm−3, respectively. In different regions of the same isothermal plane, the temperature gradually decreased from the center to the edge. The foaming quality in the region (c) at a temperature of 335.86 K was ideal, and the average diameter of cell and the cell density were 26.5 µm and 2.39 × 1010 cells·cm−3, respectively. This work could provide prediction for improving the foaming quality of foamed polyolefin composites.

Plane waves in Moore–Gibson–Thompson thermoelasticity considering nonlocal elasticity effect

The Moore–Gibson–Thompson (MGT) generalized thermoelasticity theory together with the Eringen’s nonlocal elasticity model is used to study the propagation of harmonic plane waves in an infinite elastic medium that conducts heat. Two sets of coupled longitudinal thermoelastic waves have been initiated. These waves are dispersive in nature and experience attenuation. In conjunction with the coupled waves, there also exists one uncoupled vertically shear–type (SV-type) wave. The SV-type wave is dispersive in nature but without any attenuation. The elastic nonlocality parameter influences all these waves. Furthermore, the SV-type wave faces critical frequency, while the coupled longitudinal waves may face critical frequencies conditionally. We also explore the problem of reflection of thermoelastic waves at a stress-free insulated and isothermal plane boundary of the medium considered here. The reflection coefficients and their respective energy ratios of the reflected waves to that of incident wave are determined analytically and numerically by considering an appropriate material. The numerical results are presented graphically to highlight the effects of various parameters of interest. Some important observations about the prediction of the MGT model in comparison to the other existing models (Lord–Shulman (LS) and the Green–Nagdhi theory of type III (GN-III) models) are highlighted.

The impact of the movement of the gyrotactic microorganisms on the heat and mass transfer characteristics of Casson nanofluid

This article focuses on analyzing the impact of the movement of gyrotactic microorganisms on the heat and mass transfer characteristics of Casson nanofluid flowing between divergent. Further, the analysis is performed through simulation to have a better understanding of the impact. Since the microorganisms are self-propelled, they move on their own in the nanofluid due to the concentration gradient and stabilize the nanoparticle suspension. This movement of microorganisms constitutes the formation of bioconvection. Further, the random motion of nanoparticles gives rise to two major slip mechanisms termed thermophoresis and Brownian motion. The mathematical model comprising these effects is designed using partial differential equations that are converted to ordinary differential equations with the help of suitable similarity transformation. The resulting system of equations is then solved using the differential transformation method and the outcomes are interpreted through graphs. It is indicated that the nanoparticle concentration and the motile density profiles increase with the increase in Schmidt number and also, the concentration profile is found to be increasing for higher Brownian motion parameter and lower thermophoretic parameter. The simulations performed through the finite element method portrayed that the heat flow in the diverging channel is occurring along the isothermal planes.

Heat transfer analysis of the vertical closing system in light steel framing using the isothermal planes method and finite element method

The use of steel in construction is an alternative that has changed the panorama of this sector, contributing to an increase in productivity, and a reduction in waste and construction time. The Light Steel Framing (LSF) system, introduced in Brazil at the end of the 1990s, is undergoing a process of technical development and acceptance in the national civil construction market, but there are still shortcomings regarding the design, itemization and implementation of the complementary closing systems, and also regarding its thermal performance. This study employs an analytical approach that uses the isothermal planes method to calculate the resistance and thermal transmittance, and a numerical approach that uses the ANSYS software (version 15) to verify and compare these analyses. Multi-layer closures are considered, with the outer layer being made up of cement board and the inner layer of gypsum board, brokered by fiber glass insulation and air, with studs formed by C-section profiles in galvanized steel. The isothermal planes method revealed the value of 0.77 (m2.K)/W for the equivalent thermal resistance, 1.3 W/(m2.K) for the thermal transmittance, and 13.04 W/m2 for the heat conduction flux. The difference of the results when comparing the isothermal planes and numerical solution methods was 9% for thermal resistance and 8% for heat conduction flux. The obtained results showed that the heat flux is equivalent to a value around 54% greater than the heat flux value for a closure without the presence of steel profile.

On the fragility of Alfvén waves in a stratified atmosphere

ABSTRACTComplete asymptotic expansions are developed for slow, Alfvén, and fast magnetohydrodynamic waves at the base of an isothermal 3D plane stratified atmosphere. Together with existing convergent Frobenius series solutions about z = ∞, matchings are numerically calculated that illuminate the fates of slow and Alfvén waves injected from below. An Alfvén wave in a two-dimensional model is 2.5D in the sense that the wave propagates in the plane of the magnetic field but its polarization is normal to it in an ignorable horizontal direction, and the wave remains an Alfvén wave throughout. The rotation of the plane of wave propagation away from the vertical plane of the magnetic field pushes the plasma displacement vector away from horizontal, thereby coupling it to stratification. It is shown that potent slow–Alfvén coupling occurs in such 3D models. It is found that about 50 per cent of direction-averaged Alfvén wave flux generated in the low atmosphere at frequencies comparable to or greater than the acoustic cut-off can reach the top as Alfvén flux for small magnetic field inclinations θ, and this increases to 80 per cent or more with increasing θ. On the other hand, direction-averaged slow waves can be 40 per cent effective in converting to Alfvén waves at small inclination, but this reduces sharply with increasing θ and wave frequency. Together with previously explored fast–slow and fast–Alfvén couplings, this provides valuable insights into which injected transverse waves can reach the upper atmosphere as Alfvén waves, with implications for solar and stellar coronal heating and solar/stellar wind acceleration.

Evaluation of thermal bridging mitigation techniques and impact of calculation methods for lightweight steel frame external wall systems

Thermal bridging is known to affect the thermal performance of lightweight steel-framed external walls. Various manual calculation methods have been developed to estimate this impact, including the parallel path, NZS 4214 and modified zone methods, with the NZS 4214 method recently adopted for non-residential buildings by the Australian National Construction Code 2019 via its explicit reference in AS/NZS 4859.2. These methods have been validated against different wall assemblies from those currently used in the Australian context, therefore this paper aims to examine the validity of thermal bridging calculation methods in this context and evaluate the impact of mitigation methods on the overall thermal performance. We developed a set of 34 realistic external cold-formed steel-framed wall configurations based on available market products and construction practices and compared the R-values from manual calculation methods with outputs from the 2D simulation THERM. Results have shown that the NZS 4214 method as recently adopted by the Australian National Construction Code 2019 for non-residential buildings has good applicability for wall assemblies with lower R-values (R = 1.8–2.3 m 2 K/W). However, it was shown to have larger differences for calculations of walls with higher R-values (R > 2.5 m 2 K/W). The isothermal planes method can produce various results for the same building assembly, depending on which planes are assumed to be isothermal. This study has demonstrated that superior accuracy may be obtained by varying the definition of such planes depending on the R-value of the assembly. When considering designs to mitigate thermal bridging effects and improve overall wall performances, outside frame insulation and high resistance claddings have been shown to provide the best results (decreasing variation in temperature across the surface by 75%). • R-values for suite of Australian cold formed steel wall configurations assessed. • NZS4214 calculation method shown to have good applicability for low R-values. • Isothermal plane boundary location for NZS4214 requires investigation. • External insulation and high resistance claddings provide thermal bridge mitigation.

Thermal Conductivity Structure and Anisotropy of the Colossal Carbon Mesotubes

A model of a tube with a square cross-section was compiled for the mathematical analysis of the mesotube in Cartesian coordinates, with the selection of an element of a representative volume. To estimate the effective thermal conductivity of the structure, the generalized theory of conductivity with linearization of heat flux streamlines was used. The presence of anisotropy leads to the division of the problem into a separate estimate of the longitudinal and transverse thermal conductivity. The cross-section of the model was divided into elementary sections by a system of auxiliary adiabatic and isothermal planes, then the sections of the model were presented in the form of thermal resistances connected in chains - electrical circuits. Using the analogy of the identity of thermal and electrical resistances, the total conductivity of the sections and the effective thermal conductivity of the structure were determined. This methodology satisfies the test for limit transitions.

Numerical Simulation of Jeffrey Hamel Flow of Nanofluid in the Presence of Gyrotactic Microorganisms

The nonlinear differential equations play a prominent role in mathematically describing many phenomena that occur in our world. A similar set of equations appear in this paper that govern the nanofluid flow between two non-parallel walls in the presence of gyrotactic microorganisms that are responsible for bioconvection. These microorganisms ensure the safety of the appliance by avoiding the accumulation of nanoparticles and the movement of these nanoparticles within the fluid experiences major slip mechanisms as discussed by Buongiorno. Further, the orientation of the channel is described by the parameter β and based on this parameter channel is said to be converging if and the channel is diverging if . The case when corresponds to a channel with parallel walls, hence this case is ignored. Following these assumptions, the set of governing equations thus formed are made dimensionless and further solved by the Differential Transformation Method (DTM) and the outcomes are discussed through graphs. The analysis is performed for both converging and diverging orientation of the channel. The results indicate that the temperature and the concentration profiles increase with the increase in Brownian motion parameters in both divergent and convergent channels. Meanwhile, the increase in Reynolds number decreases the temperature of the nanofluid. Through the simulation, it was observed that the heat flow is taking place along the isothermal planes in the case of the diverging channel but it was uniform in the domain of the converging channel.

A 3D computer model of the CaO-MgO-Al2O3 T-x-y diagram at temperatures above 1300 °C

The research analyses the controversies surrounding the technique for the formation of a CaO-Al2O3 binary system and the nature of melting of compounds in it, i.e. whether the 12:7 compound is technically possible and whether the 1:1 and 1:2 compounds are congruently or incongruently melting compounds. It also discusses whether in the CaO-MgO-Al2O3 ternary system the following compounds can be formed: a 3:1:1 compound alone or, in addition to it, two more compounds of 1:2:8 and 2:2:14. A 3D model of the T-x-y diagram was created for the most common version, with six binary and three ternary compounds. Its high-temperature portion (above 1300°C) consisted of 234 surfaces and 85 phase regions. Ternary compounds were formed as a result of three peritectic reactions. Besides them, six quasi-peritectic and three eutecticinvariant reactions occurred in the system with the participation of the melt. The principle of construction for a threedimensional model involved a gradual transition from a phase reaction scheme (which is transformed into a scheme of uni- and invariant states) presented in a tabulated and then in a graphical form (a template of ruled surfaces and isothermal planes corresponding to invariant reactions) to a T-x-y diagram prototype (graphic images of all liquidus, solidus, and solvus surfaces). The design was concluded with the transformation of the prototype into a 3D model of the real system after the input of the base points coordinates (concentrations and temperatures) and the adjustment of curvatures of lines andsurfaces. The finished model provides a wide range of possibilities for the visualisation of the phase diagram, including the construction of any arbitrarily assigned isothermal sections and isopleths. The 3D model was designed with the help of the author’s software PD Designer (Phase Diagram Designer). To assess the quality of the 3D model, two versions of an isothermal section at 1840 °C were compared: model section and a fragment of an experimental section near Al2O3.

Spatially Developing Modes: The Darcy–Bénard Problem Revisited

In this paper, the instability resulting from small perturbations of the Darcy–Bénard system is explored. An analysis based on time–periodic and spatially developing Fourier modes is adopted. The system under examination is a horizontal porous layer saturated by a fluid. The two impermeable and isothermal plane boundaries are considered to have different temperatures, so that the porous layer is heated from below. The spatial instability for the system is defined by taking into account both the spatial growth rate of the perturbation modes and their propagation direction. A comparison with the neutral stability condition determined by using the classical spatially periodic and time–evolving Fourier modes is performed. Finally, the physical meaning of the concept of spatial instability is discussed. In contrast to the classical analysis, based on spatially periodic modes, the spatial instability analysis, involving time–periodic Fourier modes, is found to lead to the conclusion that instability occurs whenever the Rayleigh number is positive.

Inferring time-dependent distribution functions from kinematic snapshots

ABSTRACT We propose a method for constructing the time-dependent phase space distribution function (DF) of a collisionless system from an isolated kinematic snapshot. In general, the problem of mapping a single snapshot to a time-dependent function is intractable. Here, we assume a finite series representation of the DF, constructed from the spectrum of the system’s Koopman operator. This reduces the original problem to one of mapping a kinematic snapshot to a discrete spectrum rather than to a time-dependent function. We implement this mapping with a convolutional neural network. The method is demonstrated on two example models: the quantum simple harmonic oscillator and a self-gravitating isothermal plane. The latter system exhibits phase space spiral structure similar to that observed in Gaia Data Release 2.

Genesis of the Late Cretaceous Longquanzhan Gold Deposit in the Central Tan-Lu Fault Zone, Shandong Province, China: Constraints from Noble Gas and Sulfur Isotopes

The Longquanzhan deposit is one of the largest gold deposits in the Yi-Shu fault zone (central section of the Tan-Lu fault zone) in Shandong Province, China. It is an altered-rock type gold deposit in which ore bodies mainly occur at the contact zone between the overlying Cretaceous rocks and the underlying Neoarchean gneissic monzogranite. Shi et al. reported that this deposit formed at 96 ± 2 Ma using pyrite Rb–Sr dating method and represents a new gold mineralization event in the Shandong Province in 2014. In this paper, we present new He–Ar–S isotopic compositions to further decipher the sources of fluids responsible for the Longquanzhan gold mineralization. The results show that the δ34S values of pyrites vary between 0.9‰ and 4.4‰ with an average of 2.3‰. Inclusion-trapped fluids in ore sulfides have 3He/4He and 40Ar/36Ar ratios of 0.14–0.78 Ra and 482–1811, respectively. These isotopic data indicate that the ore fluids are derived from a magmatic source, which is dominated by crustal components with minor mantle contribution. Air-saturated water may be also involved in the hydrothermal system during the magmatic fluids ascending or at the shallow deposit site. We suggest that the crust-mantle mixing signature of the Longquanzhan gold deposit is genetically related to the Late Cretaceous lithospheric thinning along the Tan-Lu fault zone, which triggers constantly uplifting of the asthenosphere surface and persistent ascending of the isotherm plane to form the gold mineralization-related crustal level magma sources. This genetic model can be applied, to some extent, to explain the ore genesis of other deposits near or within the Tan-Lu fault belt.

3D Processing Maps of Cast Mg‐9Gd‐3Y Alloy and Numerical‐Experimental Verification

The hot compression behavior of Mg‐9Gd‐3Y (GW93) alloy was investigated by carrying out isothermal compression tests at the deformation temperature range of 300–450°C and strain rate range of 0.001–1s−1. Considering the influence of the strain on the formability of the GW93 alloy, three‐dimensional (3D) processing maps were established based on the dynamic material model. The 3D processing maps indicate that the formability of the material improved with the decrease of the strain rate and the increase of the heating temperature, and the material at lower heating temperature mostly underwent flow instability. The formable processing region of the hot deformation of the GW93 alloy was concentrated within the temperature range of 380–450°C and the strain rate range of 0.001–0.01 s−1. Subsequently, the 3D processing maps were embedded into the finite element (FE) software DEFORM‐3D by means of user subroutines, and the formability of GW93 alloy during the isothermal plane strain forging process was predicted. The FE simulation results revealed that the formability of the material at low strain rate improved compared with that at high strain rate under the same temperature. Finally, an isothermal plane strain forging technological experiment was carried out, and the microstructure of the formed sample was analyzed. The experimental result is in good agreement with that of the numerical simulation. Combined with microstructural observation, the accuracy of the simulation results and the 3D processing maps of the GW93 alloy was verified.

Determining the thermal resistance of a highly insulated wall containing vacuum insulation panels through experimental, calculation and numerical simulation methods

The purpose of this paper is to investigate the potential for calculation methods to determine the thermal resistance of a wall system containing vacuum insulation panels (VIPs) that has been experimentally characterised using a guarded hot box (GHB) apparatus. The VIPs used in the wall assembly have not been characterised separately to the wall assembly, and therefore exact knowledge of the thermal performance of the VIP including edge effect is not known. The calculations and simulations are completed using methods found in literature as well as manufacturer published values for the VIPs to determine the potential for calculation and simulation methods to predict the thermal resistance of the wall assembly without the exact characterisation of the VIP edge effect. The results demonstrate that disregarding the effect of VIP thermal bridges results in overestimating the thermal resistance of the wall assembly in all calculation and simulation methods, ranging from overestimates of 21% to 58%. Accounting for the VIP thermal bridges using the manufacturer advertised effective thermal conductivity of the VIPs resulted in three methods predicting the thermal resistance of the wall assembly within the uncertainty of the GHB results: the isothermal planes method, modified zone method and the 3D simulation. Of these methods only the 3D simulation can be considered a potential valid method for energy code compliance, as the isothermal planes method requires too drastic an assumption to be valid and the modified zone method requires extrapolating the zone factor beyond values which have been validated. The results of this work demonstrate that 3D simulations do show potential for use in lieu of guarded hot box testing for predicting the thermal resistance of wall assemblies containing both VIPs and steel studs. However, knowledge of the VIP effective thermal conductivity is imperative to achieve reasonable results.