Mesh Size Distribution Research Articles

Photoresponsive Gelation of Four-Armed Poly(ethylene glycol) with Photodimerizable Groups.

Standard hydrogels prepared by free radical polymerization (FRP) have heterogeneous structures with a wide mesh size distribution, which affect their mechanical and separation properties. Recent research has identified four-armed poly(ethylene glycol) (tetra-PEG) as a solution to this problem. tetra-PEG gels with a homogeneous network can be prepared and applied as high-strength gels and cell-culture substrates by reacting two types of tetra-PEG with different reactive groups at the ends. In this study, we report a photoresponsive tetra-PEG that undergoes a phase transition from a sol to a gel state in response to light. tetra-PEGs containing cinnamoyl and maleimide groups at the ends of the four-armed chains were found to gel when exposed to light. The effects of polymer concentration and light irradiation time on the gelation of tetra-PEG containing photodimerization groups were investigated. The results showed that the elastic modulus of the gel increased with the increase in the light irradiation time.

Effect of chest physiotherapy on cystic fibrosis sputum nanostructure: an experimental and theoretical approach

Cystic fibrosis (CF) is a disease characterized by the production of viscous mucoid secretions in multiple organs, particularly the airways. The pathological increase of proteins, mucin and biological polymers determines their arrangement into a three-dimensional polymeric network, affecting the whole mucus and impairing the muco-ciliary clearance which promotes inflammation and bacterial infection. Thus, to improve the efficacy of the drugs usually applied in CF therapy (e.g., mucolytics, anti-inflammatory and antibiotics), an in-depth understanding of the mucus nanostructure is of utmost importance. Drug diffusivity inside a gel-like system depends on the ratio between the diffusing drug molecule radius and the mesh size of the network. Based on our previous findings, we propose the combined use of rheology and low field NMR to study the mesh size distribution of the sputum from CF patients. Specifically, we herein explore the effects of chest physiotherapy on CF sputum characteristic as evaluated by rheology, low field NMR and the drug penetration through the mucus via mathematical simulation. These data show that chest physiotherapy has beneficial effects on patients, as it favourably modifies sputum and enhances drug penetration through the respiratory mucus.Graphical abstract

Novel Learnings of Proppant Transport Behavior in Unconventional Hydraulic Fractures

Summary Effective proppant placement has been one of the key objectives of hydraulic fracturing. Different proppant and fracture fluid characteristics and placement methodologies have been historically applied based on learnings from standard proppant transport studies with parallel plate slots. The standard test setup represents a simplified planar fracture with constant width and confined height, incorporating only basic flow characteristics, and thus, is inadequate to capture unique phenomena of proppant transport in unconventional reservoirs. In this study, proppant transport laboratory tests were conducted on a large-scale (10×20 ft) tortuous slot flow system. This novel setup incorporates many significant unconventional fracture features, including lateral and vertical tortuosity, variable width, leakoff, fluid dynamics replicating upward fracture growth, and so on. Proppant transport behavior was investigated with multiple parameters such as proppant size, density, and concentration; fracture fluid type and viscosity; pumping sequence; pump rate; and fracture properties (width, leakoff location and rate, fracture tortuosity profile, and flow directions). The detailed parametric and integrated study of test results includes analysis of proppant dune evolution, dune shape, particle-size distribution across dune, propped area, fluid, and proppant collected from leakoff and exit ports. Multiple unique phenomena occurring at tortuous interfaces were observed, including the generation of isolated pockets of proppant pack, restriction of upward movement owing to proppant bridging, and creation of discontinuous and sparsely distributed proppant pillars above the dune. The test results demonstrated a larger proppant dune angle in front of the dune peak during injection and a subsequent falloff of proppant pack with a higher percentage of smaller mesh proppant backfilling the area at and near the inlet (analogous to the wellbore). Self-segregation of proppant in slickwater as per mesh size resulted in higher percentage of smaller mesh (larger size) proppant settled near the injection point, and a higher percentage of larger mesh (smaller size) proppant placed farther in the system. These observations and novel learnings highlight that it is critical to account for tortuous fracture pathway, leakoff effects, and flow directions (both lateral and upward) to better understand proppant transport behaviors in unconventional fractures. A partially proppant-filled fracture area is recognized in unconventional fracture in addition to general classification of propped and unpropped fracture area. Using proppant with large mesh size distribution range or pumping smaller mesh proppant first in slickwater helps achieve dual benefits of higher near-wellbore conductivity and improved far-field transport. This study demonstrates and physically verifies unique proppant transport behaviors in unconventional hydraulic fractures. It also provides novel learnings that will help the industry to optimize hydraulic fracture design through the selection of optimum proppant and fluid properties with enhanced pumping strategies for overall well productivity improvement in an unconventional reservoir.

Turbulent finite element model applied for blood flow calculation in arterial bifurcation

Background and objectiveDue to the relatively low fluid velocities in major arteries and veins, blood flow is by default laminar, however, turbulence can occur as a result of stenosis or other obstacles. Hemodynamic parameters like Wall Shear Stress or Oscillatory Shear Index can be used for plaque formation prediction, and these parameters are depended on the nature of the flow. Implementation of the k-ω turbulent flow in the Finite Element solver aims to improve numerical analysis of cardio-vascular condition development and progression. Calculation of turbulent fluid flow in this paper is performed using a two-equation turbulent finite element model that can calculate values in the viscous sublayer. MethodsImplicit integration of the equations is used for determining the fluid velocity, turbulent kinetic energy and dissipation of turbulent kinetic energy. These values are calculated in the finite element nodes for each step of the incremental-iterative procedure. Developed turbulent finite element model with the customized generation of finite element meshes is used for calculating complex blood flow problems. ResultsTurbulent model is verified on an example of fluid flow in the backward-facing step channel and analysis results correspond well with the experimental ones from the literature. Further, a turbulent model is applied for the simulation of blood flow through artery bifurcation. Verification of numerical examples obtained using different commercial software packages (Ansys, COMSOL Multiphysics) ensuring usage and accuracy of PAK in-house solver. ConclusionsAnalysis results show that turbulence cannot be neglected in the modelling of cardio-vascular conditions and that cardiologists can use the proposed tools and methods for investigating the hemodynamic conditions inside the bifurcation of arteries. Appropriate agreement between experimental results, and results obtained using commercial solutions and the k-ω turbulent flow in the Finite Element solver PAK, validate methodology presented in this paper. However, small deviations between the results underline the importance of the proper boundary condition prescription and mesh size and node distribution, which is also discussed in this paper. Due to the implicit integration implemented in PAK solver, time step size has an insignificant influence on the analysis results, assuming the initial time increments are sufficiently small to ensure proper discretization of velocity and pressure pulsatile functions.

Particle Diffusivity and Free-Energy Profiles in Hydrogels from Time-Resolved Penetration Data

A combined experimental and theoretical method to simultaneously determine diffusivity and free-energy profiles of particles that penetrate into inhomogeneous hydrogel systems is presented. As the only input, arbitrarily normalized concentration profiles from fluorescence intensity data of labeled tracer particles for different penetration times are needed. The method is applied to dextran molecules of varying size that penetrate into hydrogels of polyethylene-glycol chains with different lengths that are covalently cross-linked by hyperbranched polyglycerol hubs. Extracted dextran bulk diffusivities agree well with fluorescence correlation spectroscopy data obtained separately. Empirical scaling laws for dextran diffusivities and free energies inside the hydrogel are identified as a function of the dextran mass. An elastic free-volume model that includes dextran as well as polyethylene-glycol linker flexibility quantitively describes the repulsive dextran-hydrogel interaction free energy, which is of steric origin, and furthermore suggests that the hydrogel mesh-size distribution is rather broad and particle penetration is dominated by large hydrogel pores. Particle penetration into hydrogels for steric particle-hydrogel interactions is thus suggested to be governed by an elastic size-filtering mechanism that involves the tail of the hydrogel pore-size distribution.

The Sensitivity Analysis in Topology Optimization of Hip Stem Prosthesis Using Finite Element Method

This paper discusses the results of the parameters employed sensitivity analysis in the optimization of hip stem prosthesis geometry using topology optimization techniques based on finite element methods. The study was carried out to examine the relationship of finite element parameters, such as mesh size and stress distribution, and topology optimization parameters, such as percent to retain, to the final geometry of the prosthesis stem. Topology optimization was performed using ANSYS software for hip stem prosthesis, a type of Anatomic Medullary Locking, made from titanium alloy. The results obtained from this study indicate that the selection of finite element parameters and topology optimization parameters will have a significant effect on the shape and geometry of the hip stem. The results of this analysis can be the basis for the development of hip stem shape and geometry through topology optimization techniques.

3D meso-scale modeling of concrete with a local background grid method

Concrete is a three-phase heterogeneous composite material composed of aggregate, cement mortar and its bonding interface. The complex meso-structure of concrete has a direct influence on its macroscopic mechanical properties. In this paper, a new efficient method of concrete meso-modeling is proposed based on the local background grid method. The random polyhedral aggregate is generated according to aggregate gradation and dropped directly into the background mesh one by one. The process of concrete meso-modeling is simplified compared with the traditional meso-scale model of concrete. According to the aggregate shape and its spatial position, the newly placed aggregate is encapsulated by a bounding box, in which the identification of concrete meso-components and intrusion detection of new and old aggregates are carried out. By transforming aggregate intrusion detection during the process of concrete meso-geometric modeling into overlap check of aggregate elements in the local background grid, a large number of disjoint conditions between new and old aggregates are avoided. Thus a large amount of global calculation is greatly reduced, and the efficiency of concrete meso-modeling is obviously improved. The effects of aggregate element content, element mesh size and aggregate particle size distribution on concrete meso-modeling are analyzed. Finally, the reliability and validity of the concrete meso-model are verified by numerical simulation of concrete uniaxial compression and projectile penetration into concrete.

Computational-Based Design of Hydrogels with Predictable Mesh Properties.

Hydrogel systems are an appealing class of therapeutic delivery vehicles, though it can be challenging to design hydrogels that maintain desired spatiotemporal presentation of therapeutic cargo. In this work, we propose a different approach in which computational tools are developed that creates a theoretical representation of the hydrogel polymer network to design hydrogels with predefined mesh properties critical for controlling therapeutic delivery. We postulated and confirmed that the computational model could incorporate properties of alginate polymers, including polymer content, monomer composition and polymer chain radius, to accurately predict cross-link density and mesh size for a wide range of alginate hydrogels. Additionally, the simulations provided a robust strategy to determine the mesh size distribution and identified properties to control the mesh size of alginate hydrogels. Furthermore, the model was validated for additional hydrogel systems and provided a high degree of correlation (R2 > 0.95) to the mesh sizes determined for both fibrin and polyethylene glycol (PEG) hydrogels. Finally, a full factorial and Box-Behnken design of experiments (DOE) approach utilized in combination with the computational model predicted that the mesh size of hydrogels could be varied from approximately 5 nm to 5 μm through controlling properties of the polymer network. Overall, this computational model of the hydrogel polymer network provides a rapid and accessible strategy to predict hydrogel mesh properties and ultimately design hydrogel systems with desired mesh properties for potential therapeutic applications.

An automatic approach to constrained quadrilateral mesh generation

Purpose Arbitrary constraints might be included into the problem domain in many engineering applications, which represent specific features such as multi-domain interfaces, cracks with small yield stresses, stiffeners attached on the plate for reinforcement and so on. To imprint these constraints into the final mesh, additional techniques need to be developed to treat these constraints properly. Design/methodology/approach This paper proposes an automatic approach to generate quadrilateral meshes for the geometric models with complex feature constraints. Firstly, the region is decomposed into sub-regions by the constraints, and then the quadrilateral mesh is generated in each sub-region that satisfies the constraints. A method that deals with constraint lines and points is presented. A distribution function is proposed to represent the distribution of mesh size over the region by using the Laplace equation. The density lines and points can be specified inside the region and reasonable mesh size distribution can be obtained by solving the Laplace equation. Findings An automatic method to define sub-regions is presented, and the user interaction can be avoided. An algorithm for constructing loops from constraint lines is proposed, which can deal with the randomly distributed constraint lines in a general way. A method is developed to deal with constraint points and quality elements can be generated around constraint points. A function defining the distribution of mesh size is put forward. The examples of constrained quadrilateral mesh generation in actual engineering analysis are presented to show the performance of the approach. Originality/value An automatic approach to constrained quadrilateral mesh generation is presented in this paper. It can generate required quality meshes for special applications with complex internal feature constraints.

Aging of natural rubber studied via Fourier-transform rheology and double quantum NMR to correlate local chain dynamics with macroscopic mechanical response

Nowadays mainly the linear rheological properties of natural rubber (NR) vulcanizate during aging are studied, even though NR is rheologically nonlinear under most application conditions. Here, the nonlinearity was quantified via Fourier transform rheology (FT-Rheology) using I3/1, the relative intensity of the 3rd harmonic. The crosslink density and the content of defects were investigated by the 1H double quantum nuclear magnetic resonance (DQ-NMR). For aerobic aging at 120 °C, the crosslink density increases, but later turns into a broader mesh size distribution with more defects. Accordingly, the rheological nonlinearity of the material increases in the earlier stage and then decreases. For mechanical aging, the nonlinearity continuously decreases as a function of the fatigue cycle numbers, whereas the local crosslink density of the polymer network remains constant. This behavior can be assigned to the micro-cracks generated along adjacent network defects, which are larger than the detection scale of DQ-NMR. Compared to the linear rheological parameters, storage modulus G′ and loss factor tanδ, I3/1 exhibits higher sensitivity to the aging of crosslinked NR under both high temperature aerobic and mechanical fatigue conditions.

Theoretical Importance of PVP-Alginate Hydrogels Structure on Drug Release Kinetics.

Background: The new concepts of personalized and precision medicine require the design of more and more refined delivery systems. In this frame, hydrogels can play a very important role as they represent the best surrogate of soft living tissues for what concerns rheological properties. Thus, this paper focusses on a global theoretical approach able to describe how hydrogel polymeric networks can affect the release kinetics of drugs characterized by different sizes. The attention is focused on a case study dealing with an interpenetrated hydrogel made up by alginate and poly(N-vinyl-2-pyrrolidone). Methods: Information about polymeric network characteristics (mesh size distribution and polymer volume fraction) is deduced from the theoretical interpretation of the rheological and the low field Nuclear Magnetic Resonance (NMR) characterization of hydrogels. This information is then, embodied in the mass balance equation whose resolution provides the release kinetics. Results: Our simulations indicate the influence of network characteristics on release kinetics. In addition, the reliability of the proposed approach is supported by the comparison of the model outcome with experimental release data. Conclusions: This study underlines the necessity of a global theoretical approach in order to design reliable delivery systems based on hydrogels.

Use of low-field NMR for the characterization of gels and biological tissues

The focus of this paper is on the theoretical interpretation of Low Field Nuclear Magnetic Resonance (LF-NMR) data regarding hydrogels architecture and on the most interesting applications of LF-NMR presented by this research group at the 6<sup>th</sup> IAPC Symposium held in Zagreb (HR) on September 2017. Particular attention is devoted to the determination of the mesh size distribution of gels polymeric network and the determination of the pore size distribution of microporous systems such as scaffolds, bones, and porous gels. In addition, we report on a very recent application of LF-NMR for monitoring lung functioning in patients suffering from chronic pulmonary diseases like cystic fibrosis. The main findings of this work consist in providing a very simple and accurate approximation of a general theory devoted to evaluating the relation existing among four fundamental polymeric network parameters, i.e. the polymer volume fraction inside the hydrogel, mesh size, hydraulic radius, and the radius of the cylinder ideally embedding each polymeric network chain. Furthermore, we demonstrated the potentiality of LF-NMR in the characterization of different polymeric systems among which the sputum of patients suffering from chronic pulmonary diseases appears the most innovative application for its simplicity, rapidity, effectiveness, and potential impact in the everyday clinic.

Massively parallel anisotropic mesh adaptation

Mesh adaptation has proven to be very efficient for simulating transient multiphase computational fluid dynamics applications. In this work, we present a new parallel anisotropic mesh adaptation technique relying on an edge based error estimator. It provides a high level of accuracy while substantially reducing the computational effort. This technique enables a good capture of physical phenomena, boundary layers, interfaces, free surfaces and even multiphase turbulent flows, and has a great potential to simulate a large variety of applications. Current investigations explore the performance of the new algorithm on massively parallel resources. In this paper, we show that the developed adaptive meshing works very well in a parallel environment involving topological mesh modifications and dynamic repartitioning of parallel slots. It is also shown that the proposed methodology provides an additional gain in terms of computational cost due the production of a non-uniform mesh size distribution. Runs performed on national and European supercomputers will show the scalability and pertinence of our developments.

Anisotropic boundary layer mesh generation for immersed complex geometries

This paper proposes a new method to build boundary layer meshes over an immersed complex geometry. It allows to generate an anisotropic semi-structured mesh with a smooth gradation of mesh size from a geometry immersed into an arbitrary coarse domain, while capturing and keeping the interface. The idea is to generate an a priori mesh fitting the geometry boundary layer which is ready for simulations. The mesh size distribution is driven by a levelset distance function and is determined using physical parameters available before the simulation, based on the boundary layer theory. The aspect ratio is then determined knowing the shape of the geometry, and all is applied in a metric tensor field using a gradation thanks to the new multi-levelset method. Then, the mesh generator adapt the initial mesh on the given metric field to create the desired boundary layer mesh.

Synthesis and characterization of UV photocrosslinkable hydrogels with poly(N-vinyl-2-pyrrolidone): Determination of the network mesh size distribution

ABSTRACTHydrogels of poly(n-vinyl-2-pyrrolidone) were produced by UV irradiation of aqueous solutions of the polymer in presence of hydrogen peroxide, used as initiator. The mechanical and the nanostructural properties of the gels were characterized by a combination of experimental techniques including rheology, low field nuclear magnetic resonance spectroscopy (LF-NMR), and small angle X-ray scattering. Different irradiation doses as well as polymer and initiator concentrations were tested in the characterization. The study elucidates the relationship between different methods to estimate the mesh size of the gel polymeric network. Moreover, a novel correlation model was developed based on Chui and Scherer theories for the interpretation of LF-NMR dataset of polymer solutions and networks.

Synthesis of organic‐inorganic hybrid gels by means of thiol‐ene and azide‐alkene reactions

ABSTRACTOrganic–inorganic hybrid gels have been synthesized from a multi‐vinyl functional cyclic siloxane, 1,3,5,7‐tetravinyltetramethylcyclotetrasiloxane (TVMCTS), or a cubic silsesquioxane, octavinyloctasilasesquioxane (PVOSS), and α,ω‐dithiol compounds, 1,6‐hexanedithiol (HDT), 1,10‐decanedithiol (DDT), using thiol‐ene reaction in toluene. The network structure of the resulting gels, mesh size and mesh size distribution, was quantitatively characterized by means of a scanning microscopic light scattering (SMILS). The gels obtained from TVMCTS‐HDT formed homogeneous network structure with 1.5–1.6 nm mesh. Relaxation peaks derived from large clusters and/or micro gels were detected in the SMILS analysis of the TVMCTS‐DDT, PVOSS‐HDT, and PVOSS‐DDT gels besides those from the small meshes. The organic–inorganic hybrid gels were also synthesized from TVMCTS, PVOSS with α,ω‐diazide compounds, 1,6‐hexanediazide (HDA), 1,10‐decanediazide (DDA), using azide‐alkene reaction in toluene. All the gels obtained with the azide‐alkene reaction formed the homogeneous network structure. Enthalpy relaxation at the glass transition of the dried samples was detected by differential scanning calorimetry to study the network uniformity of the original gels. The gels synthesized by the azide‐alkene reaction showed larger enthalpy than the gels synthesized by the thiol‐ene reaction, indicating homogeneous network structure in the former gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2229–2238

Synthesis and Structure of Organic-Inorganic Hybrid Semi-interpenetrating Polymer Network Gels

Semi-interpenetrating polymer network (semi-IPN) gels have been synthesized using a hydrosilylation reaction of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) as a joint molecule, and a,w-nonconjugated dienes, 1,5-hexadiene (HD) or 1,9-decadiene (DD) as linker molecules in the presence of polystyrene (PS) as a liner polymers in toluene or cyclohexane. Network structure, mesh size and mesh size distribution, of the resulting semi-IPN gels was quantitatively characterized by means of a scanning microscopic light scattering (SMILS). The relaxation peaks derived from three kinds of structures were detected in the semi-IPN gels prepared in toluene by the SMILS analysis. One was derived from the mesh formed by TMCTS/a,w-nonconjugated dienes about 1-2 nm. Others were derived from transition networks about 20-150 nm and large clustered liner polymer chains about 700-2300 nm. Effect of concentration and molecular weight of the liner polymer on the network structure of the semi-IPN gels in toluene was investigated. The relaxation peaks derived from transition networks or random coils formed by aggregated PS chains were detected in the semi-IPN gels containing high concentration or high molecular weight PS. The semi-IPN gels containing PS were also prepared in cyclohexane as a poor solvent for PS at 40ºC, which was a higher temperature than the upper critical solution temperature (UCST = 34ºC) of PS in cyclohexane. The network structure of the semi-IPN gels was traced by SMILS on the cooling process. In the semi-IPN gel with the short linker molecule of HD, the relaxation peak derived from clustered PS chains was detected over the UCST. By contrast, the relaxation peak derived from transition network was observed in the semi-IPN gel with the long linker molecule of DD.

Diels-Alder Hydrogels for Controlled Antibody Release: Correlation between Mesh Size and Release Rate.

Eight-armed PEG, molecular mass 10 kDa, was functionalized with furyl and maleimide groups, respectively; the obtained macromonomers were cross-linked via Diels-Alder chemistry. The mesh size (ξ) of the prepared hydrogels was determined by swelling studies, rheology, and low field NMR spectroscopy. The in vitro release of fluorescein isothiocyanate labeled dextrans (FDs) and bevacizumab was investigated. The average mesh size (ξavg) increased from 5.8 ± 0.1 nm to 56 ± 13 nm during degradation, as determined by swelling studies. The result of the rheological measurements (8.0 nm) matched the initial value of ξavg. Low field NMR spectroscopy enabled the determination of the mesh size distribution; the most abundant mesh size was found to be 9.2 nm. In combination with the hydrodynamic radius of the molecule (Rh), the time-dependent increase of ξavg was used to predict the release profiles of incorporated FDs applying an obstruction-scaling model. The predicted release profiles matched the experimentally determined release profiles when Rh < ξavg. However, significant deviations from the theoretical predictions were observed when Rh ≥ ξavg, most likely due to the statistical distribution of ξ in real polymer networks. The release profile of bevacizumab differed from those of equivalently sized FDs. The delayed release of bevacizumab was most likely a result of the globular structure and rigidity of the protein. The observed correlation between ξ and the release rate could facilitate the design of controlled release systems for antibodies.

Physical characterization of alginate–Pluronic F127 gel for endoluminal NABDs delivery

Here we focus the attention on the physical characteristics of a highly biocompatible hydrogel made up of crosslinked alginate and Pluronic F127 (PF127). This is a composite polymeric blend we propose for artery endoluminal delivery of an emerging class of molecules named nucleic acid based drugs (NABDs). The physical characterization of our composite gel, i.e. mesh size distribution and PF127-alginate mutual organization after crosslinking, can significantly determine the NABDs release kinetics. Thus, to explore these aspects, different technical approaches, i.e. rheology, low/high field NMR and TEM, were used. While rheology provided information at the macroscopic and nano-level, the other three approaches gave details at the nano-level. We observe that Pluronic micelles, organizing in cubic ordered domains, generate, upon alginate crosslinking, the formation of meshes (≈ 150 nm) larger than those occurring in a Pluronic-free alginate network (≈ 25 nm). Nevertheless, smaller alginate meshes are still on and can just host un-structured Pluronic micelles and water. Accordingly, the gel structure is quite inhomogeneous, where big meshes (filled by crystalline Pluronic) co-exist with smaller meshes (hosting water and un-structured PF127 micelles). While big meshes offer a considerable hindering action on a diffusing solute, smaller ones represent a sort of free space where solute diffusion is faster. The presence of big and small meshes indicates that drug release may follow a double kinetics characterized by a fast and slow release. Notably, this behavior is considered appropriate for endoluminal drug release to the arterial wall.

An immersed boundary–body conformal enrichment method for thermal flow problems

Solving the flow around objects with complex shapes may involve extensive meshing work that has to be repeated each time a change in the geometry is needed. The same problem arises if one need to solve the heat transfer involving multiple materials whose interface is complex or changes with time. Time consuming meshing can be avoided when the solution algorithm can tackle grids that do not fit the shape of the interface between different materials. This work presents the extension of a recently proposed immersed boundary–body conformal enrichment (IB–BCE) method to the solution of the heat transfer. The method produces solutions of the temperature field satisfying accurately the continuity of the normal heat flux at interfaces between materials with different thermal properties. As for the isothermal flow problems, the fluid/solid interface is defined using a level-set function and the finite element discretization of interface elements is enriched with additional degrees of freedom which are eliminated at element level. The method is first validated in the case of heat conduction in two solids with different thermal properties. Then, solutions are shown for the more complex conjugate heat transfer between water and aluminum for two configurations: steady state flow inside a channel obstructed by a heated cylinder and transient flow around a heated cylinder. For each problem the solutions obtained using the proposed immersed boundary method are compared with solutions on body-conformal meshes having comparable mesh size distribution. The proposed approach is very accurate and effective in capturing the sharp discontinuity in the normal temperature gradient at the interface.